645895656 has 288 divisors, whose sum is σ = 2160756000. Its totient is φ = 173521152.

The previous prime is 645895589. The next prime is 645895661. The reversal of 645895656 is 656598546.

645895656 is a `hidden beast` number, since 6 + 4 + 589 + 5 + 6 + 56 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 6036355 + ... + 6036461.

It is an arithmetic number, because the mean of its divisors is an integer number (7502625).

Almost surely, 2^645895656 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645895656, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1080378000).

645895656 is an abundant number, since it is smaller than the sum of its proper divisors (1514860344).

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

645895656 is a wasteful number, since it uses less digits than its factorization.

645895656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 221 (or 207 counting only the distinct ones).

The product of its digits is 7776000, while the sum is 54.

The square root of 645895656 is about 25414.4772914967. The cubic root of 645895656 is about 864.4120012926.

The spelling of 645895656 in words is "six hundred forty-five million, eight hundred ninety-five thousand, six hundred fifty-six".