656772391 has 12 divisors (see below), whose sum is σ = 732690616. Its totient is φ = 588147120.

The previous prime is 656772379. The next prime is 656772401. The reversal of 656772391 is 193277656.

656772391 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 656772391 - 2¹⁵ = 656739623 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (656772331) 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, 32400 + ... + 48613.

Almost surely, 2^656772391 is an apocalyptic number.

656772391 is a deficient number, since it is larger than the sum of its proper divisors (75918225).

656772391 is a wasteful number, since it uses less digits than its factorization.

656772391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81102 (or 81091 counting only the distinct ones).

The product of its digits is 476280, while the sum is 46.

The square root of 656772391 is about 25627.5709149346. The cubic root of 656772391 is about 869.2371835618.

The spelling of 656772391 in words is "six hundred fifty-six million, seven hundred seventy-two thousand, three hundred ninety-one".