656121517880166 has 96 divisors (see below), whose sum is σ = 1548437852052000. Its totient is φ = 199578319041024.

The previous prime is 656121517880161. The next prime is 656121517880281. The reversal of 656121517880166 is 661088715121656.

It is a happy number.

656121517880166 is a `hidden beast` number, since 6 + 5 + 6 + 1 + 21 + 517 + 8 + 80 + 16 + 6 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (656121517880161) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 109949200 + ... + 115762988.

It is an arithmetic number, because the mean of its divisors is an integer number (16129560958875).

Almost surely, 2^{656121517880166} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 656121517880166, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (774218926026000).

656121517880166 is an abundant number, since it is smaller than the sum of its proper divisors (892316334171834).

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

656121517880166 is a wasteful number, since it uses less digits than its factorization.

656121517880166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5819318 (or 5819315 counting only the distinct ones).

The product of its (nonzero) digits is 29030400, while the sum is 63.

The spelling of 656121517880166 in words is "six hundred fifty-six trillion, one hundred twenty-one billion, five hundred seventeen million, eight hundred eighty thousand, one hundred sixty-six".