656956597721 has 16 divisors (see below), whose sum is σ = 665276405760. Its totient is φ = 648695193600.

The previous prime is 656956597681. The next prime is 656956597727. The reversal of 656956597721 is 127795659656.

It is a cyclic number.

It is not a de Polignac number, because 656956597721 - 2³⁰ = 655882855897 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (656956597727) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 25302296 + ... + 25328246.

It is an arithmetic number, because the mean of its divisors is an integer number (41579775360).

Almost surely, 2^656956597721 is an apocalyptic number.

It is an amenable number.

656956597721 is a deficient number, since it is larger than the sum of its proper divisors (8319808039).

656956597721 is a wasteful number, since it uses less digits than its factorization.

656956597721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27064.

The product of its digits is 214326000, while the sum is 68.

The spelling of 656956597721 in words is "six hundred fifty-six billion, nine hundred fifty-six million, five hundred ninety-seven thousand, seven hundred twenty-one".