656621566811 has 12 divisors (see below), whose sum is σ = 763903833480. Its totient is φ = 562760462880.

The previous prime is 656621566807. The next prime is 656621566817. The reversal of 656621566811 is 118665126656.

It is a happy number.

It is not a de Polignac number, because 656621566811 - 2² = 656621566807 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (656621566817) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 207185 + ... + 1164546.

It is an arithmetic number, because the mean of its divisors is an integer number (63658652790).

Almost surely, 2^656621566811 is an apocalyptic number.

656621566811 is a deficient number, since it is larger than the sum of its proper divisors (107282266669).

656621566811 is a wasteful number, since it uses less digits than its factorization.

656621566811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1381514 (or 1381507 counting only the distinct ones).

The product of its digits is 3110400, while the sum is 53.

The spelling of 656621566811 in words is "six hundred fifty-six billion, six hundred twenty-one million, five hundred sixty-six thousand, eight hundred eleven".