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12780 = 2232571
BaseRepresentation
bin11000111101100
3122112100
43013230
5402110
6135100
752155
oct30754
918470
1012780
119669
127490
135a81
14492c
153bc0
hex31ec

12780 has 36 divisors (see below), whose sum is σ = 39312. Its totient is φ = 3360.

The previous prime is 12763. The next prime is 12781. The reversal of 12780 is 8721.

12780 is nontrivially palindromic in base 11.

It is a tau number, because it is divible by the number of its divisors (36).

It is a hoax number, since the sum of its digits (18) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is not an unprimeable number, because it can be changed into a prime (12781) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 145 + ... + 215.

It is an arithmetic number, because the mean of its divisors is an integer number (1092).

212780 is an apocalyptic number.

12780 is a gapful number since it is divisible by the number (10) 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 12780, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (19656).

12780 is an abundant number, since it is smaller than the sum of its proper divisors (26532).

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

12780 is a wasteful number, since it uses less digits than its factorization.

12780 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 86 (or 81 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 18.

The square root of 12780 is about 113.0486620885. The cubic root of 12780 is about 23.3799521474.

The spelling of 12780 in words is "twelve thousand, seven hundred eighty".

Divisors: 1 2 3 4 5 6 9 10 12 15 18 20 30 36 45 60 71 90 142 180 213 284 355 426 639 710 852 1065 1278 1420 2130 2556 3195 4260 6390 12780