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231540 = 223517227
BaseRepresentation
bin111000100001110100
3102202121120
4320201310
524402130
64543540
71653021
oct704164
9382546
10231540
11148a61
12b1bb0
138150a
1460548
1548910
hex38874

231540 has 48 divisors (see below), whose sum is σ = 689472. Its totient is φ = 57856.

The previous prime is 231533. The next prime is 231547. The reversal of 231540 is 45132.

231540 is a nontrivial binomial coefficient, being equal to C(681, 2).

It is an interprime number because it is at equal distance from previous prime (231533) and next prime (231547).

It is a super-2 number, since 2×2315402 = 107221543200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (231547) by changing a digit.

231540 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 907 + ... + 1133.

It is an arithmetic number, because the mean of its divisors is an integer number (14364).

2231540 is an apocalyptic number.

231540 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

231540 is the 680-th triangular number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 231540, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (344736).

231540 is an abundant number, since it is smaller than the sum of its proper divisors (457932).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

231540 is a wasteful number, since it uses less digits than its factorization.

231540 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 256 (or 254 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 15.

The square root of 231540 is about 481.1860347101. The cubic root of 231540 is about 61.4056985590.

Adding to 231540 its reverse (45132), we get a palindrome (276672).

The spelling of 231540 in words is "two hundred thirty-one thousand, five hundred forty".

Divisors: 1 2 3 4 5 6 10 12 15 17 20 30 34 51 60 68 85 102 170 204 227 255 340 454 510 681 908 1020 1135 1362 2270 2724 3405 3859 4540 6810 7718 11577 13620 15436 19295 23154 38590 46308 57885 77180 115770 231540