665520216172 has 18 divisors (see below), whose sum is σ = 1354809011892. Its totient is φ = 285222949704.

The previous prime is 665520216157. The next prime is 665520216191. The reversal of 665520216172 is 271612025566.

It is a super-2 number, since 2×665520216172² (a number of 24 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1697755458 + ... + 1697755849.

Almost surely, 2^665520216172 is an apocalyptic number.

It is an amenable number.

665520216172 is an abundant number, since it is smaller than the sum of its proper divisors (689288795720).

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

665520216172 is a wasteful number, since it uses less digits than its factorization.

665520216172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3395511325 (or 3395511316 counting only the distinct ones).

The product of its (nonzero) digits is 302400, while the sum is 43.

The spelling of 665520216172 in words is "six hundred sixty-five billion, five hundred twenty million, two hundred sixteen thousand, one hundred seventy-two".