661813726272 has 56 divisors (see below), whose sum is σ = 1752080316000. Its totient is φ = 220474622976.

The previous prime is 661813726261. The next prime is 661813726291. The reversal of 661813726272 is 272627318166.

It is a happy number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 688197 + ... + 1340612.

It is an arithmetic number, because the mean of its divisors is an integer number (31287148500).

Almost surely, 2^661813726272 is an apocalyptic number.

It is an amenable number.

661813726272 is an abundant number, since it is smaller than the sum of its proper divisors (1090266589728).

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

661813726272 is a wasteful number, since it uses less digits than its factorization.

661813726272 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2030523 (or 2030513 counting only the distinct ones).

The product of its digits is 2032128, while the sum is 51.

The spelling of 661813726272 in words is "six hundred sixty-one billion, eight hundred thirteen million, seven hundred twenty-six thousand, two hundred seventy-two".