665666877855850 has 24 divisors (see below), whose sum is σ = 1333381961491020. Its totient is φ = 245784693361920.

The previous prime is 665666877855799. The next prime is 665666877855857. The reversal of 665666877855850 is 58558778666566.

It can be written as a sum of positive squares in 6 ways, for example, as 314346623611329 + 351320254244521 = 17729823^2 + 18743539^2 .

It is a super-2 number, since 2×665666877855850² (a number of 30 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (665666877855857) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 512051443855 + ... + 512051445154.

Almost surely, 2^{665666877855850} is an apocalyptic number.

665666877855850 is an abundant number, since it is smaller than the sum of its proper divisors (667715083635170).

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

665666877855850 is a wasteful number, since it uses less digits than its factorization.

665666877855850 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1024102889034 (or 1024102889029 counting only the distinct ones).

The product of its (nonzero) digits is 121927680000, while the sum is 88.

The spelling of 665666877855850 in words is "six hundred sixty-five trillion, six hundred sixty-six billion, eight hundred seventy-seven million, eight hundred fifty-five thousand, eight hundred fifty".