12565656440 has 128 divisors (see below), whose sum is σ = 29248801920. Its totient is φ = 4856832000.

The previous prime is 12565656431. The next prime is 12565656443. The reversal of 12565656440 is 4465656521.

It is a super-2 number, since 2×12565656440² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 12565656391 and 12565656400.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (12565656443) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 40403885 + ... + 40404195.

It is an arithmetic number, because the mean of its divisors is an integer number (228506265).

Almost surely, 2^12565656440 is an apocalyptic number.

12565656440 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 12565656440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (14624400960).

12565656440 is an abundant number, since it is smaller than the sum of its proper divisors (16683145480).

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

12565656440 is a wasteful number, since it uses less digits than its factorization.

12565656440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 633 (or 629 counting only the distinct ones).

The product of its (nonzero) digits is 864000, while the sum is 44.

The spelling of 12565656440 in words is "twelve billion, five hundred sixty-five million, six hundred fifty-six thousand, four hundred forty".