656256640 has 64 divisors (see below), whose sum is σ = 1689566760. Its totient is φ = 242307072.

The previous prime is 656256553. The next prime is 656256649. The reversal of 656256640 is 46652656.

It can be written as a sum of positive squares in 4 ways, for example, as 363436096 + 292820544 = 19064^2 + 17112^2 .

It is a tau number, because it is divible by the number of its divisors (64).

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 656256593 and 656256602.

It is not an unprimeable number, because it can be changed into a prime (656256649) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 31119 + ... + 47758.

Almost surely, 2^656256640 is an apocalyptic number.

It is an amenable number.

656256640 is an abundant number, since it is smaller than the sum of its proper divisors (1033310120).

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

656256640 is a wasteful number, since it uses less digits than its factorization.

656256640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78909 (or 78897 counting only the distinct ones).

The product of its (nonzero) digits is 259200, while the sum is 40.

The square root of 656256640 is about 25617.5065141009. The cubic root of 656256640 is about 869.0095921091.

The spelling of 656256640 in words is "six hundred fifty-six million, two hundred fifty-six thousand, six hundred forty".