721673800155 has 128 divisors (see below), whose sum is σ = 1651153305600. Its totient is φ = 290241532800.

The previous prime is 721673800117. The next prime is 721673800163. The reversal of 721673800155 is 551008376127.

It is a happy number.

721673800155 is a `hidden beast` number, since 7 + 216 + 7 + 380 + 0 + 1 + 55 = 666.

It is not a de Polignac number, because 721673800155 - 2¹⁶ = 721673734619 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 721673800155.

It is an unprimeable number.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 797515 + ... + 1442004.

It is an arithmetic number, because the mean of its divisors is an integer number (12899635200).

Almost surely, 2^721673800155 is an apocalyptic number.

721673800155 is an abundant number, since it is smaller than the sum of its proper divisors (929479505445).

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

721673800155 is a wasteful number, since it uses less digits than its factorization.

721673800155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2239582 (or 2239576 counting only the distinct ones).

The product of its (nonzero) digits is 352800, while the sum is 45.

The spelling of 721673800155 in words is "seven hundred twenty-one billion, six hundred seventy-three million, eight hundred thousand, one hundred fifty-five".