656387691 has 4 divisors (see below), whose sum is σ = 875183592. Its totient is φ = 437591792.

The previous prime is 656387671. The next prime is 656387701. The reversal of 656387691 is 196783656.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 656387691 - 2¹³ = 656379499 is a prime.

It is a super-2 number, since 2×656387691² = 861689601792622962, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (656387621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 109397946 + ... + 109397951.

It is an arithmetic number, because the mean of its divisors is an integer number (218795898).

Almost surely, 2^656387691 is an apocalyptic number.

656387691 is a deficient number, since it is larger than the sum of its proper divisors (218795901).

656387691 is a wasteful number, since it uses less digits than its factorization.

656387691 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 218795900.

The product of its digits is 1632960, while the sum is 51.

The square root of 656387691 is about 25620.0642270858. The cubic root of 656387691 is about 869.0674338076.

The spelling of 656387691 in words is "six hundred fifty-six million, three hundred eighty-seven thousand, six hundred ninety-one".