651561555656 has 32 divisors (see below), whose sum is σ = 1336997556000. Its totient is φ = 295218119040.

The previous prime is 651561555599. The next prime is 651561555811. The reversal of 651561555656 is 656555165156.

It is a Smith number, since the sum of its digits (56) coincides with the sum of the digits of its prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11800106 + ... + 11855193.

It is an arithmetic number, because the mean of its divisors is an integer number (41781173625).

Almost surely, 2^651561555656 is an apocalyptic number.

It is an amenable number.

651561555656 is an abundant number, since it is smaller than the sum of its proper divisors (685436000344).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

651561555656 is a wasteful number, since it uses less digits than its factorization.

651561555656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23655629 (or 23655625 counting only the distinct ones).

The product of its digits is 20250000, while the sum is 56.

The spelling of 651561555656 in words is "six hundred fifty-one billion, five hundred sixty-one million, five hundred fifty-five thousand, six hundred fifty-six".