661673137600 has 84 divisors (see below), whose sum is σ = 1639843177000. Its totient is φ = 262765071360.

The previous prime is 661673137583. The next prime is 661673137661. The reversal of 661673137600 is 6731376166.

It is a happy number.

It is a super-2 number, since 2×661673137600² (a number of 24 digits) contains 22 as substring.

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, 1265175 + ... + 1709974.

Almost surely, 2^661673137600 is an apocalyptic number.

It is an amenable number.

661673137600 is an abundant number, since it is smaller than the sum of its proper divisors (978170039400).

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

661673137600 is a wasteful number, since it uses less digits than its factorization.

661673137600 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2975310 (or 2975295 counting only the distinct ones).

The product of its (nonzero) digits is 571536, while the sum is 46.

The spelling of 661673137600 in words is "six hundred sixty-one billion, six hundred seventy-three million, one hundred thirty-seven thousand, six hundred".