128521597681656 has 48 divisors (see below), whose sum is σ = 366399291640200. Its totient is φ = 40585767688512.

The previous prime is 128521597681643. The next prime is 128521597681691. The reversal of 128521597681656 is 656186795125821.

128521597681656 is a `hidden beast` number, since 1 + 2 + 8 + 5 + 21 + 597 + 6 + 8 + 1 + 6 + 5 + 6 = 666.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 46974266791 + ... + 46974269526.

Almost surely, 2^{128521597681656} is an apocalyptic number.

It is an amenable number.

128521597681656 is an abundant number, since it is smaller than the sum of its proper divisors (237877693958544).

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

128521597681656 is a wasteful number, since it uses less digits than its factorization.

128521597681656 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 93948536348 (or 93948536341 counting only the distinct ones).

The product of its digits is 435456000, while the sum is 72.

The spelling of 128521597681656 in words is "one hundred twenty-eight trillion, five hundred twenty-one billion, five hundred ninety-seven million, six hundred eighty-one thousand, six hundred fifty-six".