656511215661 has 24 divisors (see below), whose sum is σ = 1083848323584. Its totient is φ = 375120266400.

The previous prime is 656511215641. The next prime is 656511215699. The reversal of 656511215661 is 166512115656.

656511215661 is a `hidden beast` number, since 6 + 5 + 6 + 511 + 21 + 56 + 61 = 666.

It is not a de Polignac number, because 656511215661 - 2¹⁵ = 656511182893 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (656511215621) 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 23 ways as a sum of consecutive naturals, for example, 432315 + ... + 1224711.

It is an arithmetic number, because the mean of its divisors is an integer number (45160346816).

Almost surely, 2^656511215661 is an apocalyptic number.

It is an amenable number.

656511215661 is a deficient number, since it is larger than the sum of its proper divisors (427337107923).

656511215661 is a wasteful number, since it uses less digits than its factorization.

656511215661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 805561 (or 805558 counting only the distinct ones).

The product of its digits is 324000, while the sum is 45.

The spelling of 656511215661 in words is "six hundred fifty-six billion, five hundred eleven million, two hundred fifteen thousand, six hundred sixty-one".