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261020 = 22531421
BaseRepresentation
bin111111101110011100
3111021001102
4333232130
531323040
65332232
72134664
oct775634
9437042
10261020
11169121
12107078
1391a66
146b1a4
1552515
hex3fb9c

261020 has 24 divisors (see below), whose sum is σ = 567168. Its totient is φ = 100800.

The previous prime is 261017. The next prime is 261031. The reversal of 261020 is 20162.

261020 = T59 + T60 + ... + T120.

It is a junction number, because it is equal to n+sod(n) for n = 260992 and 261010.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 410 + ... + 830.

It is an arithmetic number, because the mean of its divisors is an integer number (23632).

2261020 is an apocalyptic number.

261020 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261020, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (283584).

261020 is an abundant number, since it is smaller than the sum of its proper divisors (306148).

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

261020 is a wasteful number, since it uses less digits than its factorization.

With its predecessor (261019) it forms a Ruth-Aaron pair, since the sum of their prime factors is the same (461).

261020 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 461 (or 459 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 11.

The square root of 261020 is about 510.9011646101. The cubic root of 261020 is about 63.9083975990.

Adding to 261020 its reverse (20162), we get a palindrome (281182).

The spelling of 261020 in words is "two hundred sixty-one thousand, twenty".

Divisors: 1 2 4 5 10 20 31 62 124 155 310 421 620 842 1684 2105 4210 8420 13051 26102 52204 65255 130510 261020