721706724 has 36 divisors (see below), whose sum is σ = 1858740156. Its totient is φ = 236029248.

The previous prime is 721706717. The next prime is 721706743. The reversal of 721706724 is 427607127.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 238146624 + 483560100 = 15432^2 + 21990^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

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, 187219 + ... + 191034.

It is an arithmetic number, because the mean of its divisors is an integer number (51631671).

Almost surely, 2^721706724 is an apocalyptic number.

It is an amenable number.

721706724 is an abundant number, since it is smaller than the sum of its proper divisors (1137033432).

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

721706724 is a wasteful number, since it uses less digits than its factorization.

721706724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 378316 (or 378311 counting only the distinct ones).

The product of its (nonzero) digits is 32928, while the sum is 36.

The square root of 721706724 is about 26864.5998295154. The cubic root of 721706724 is about 896.9885868579.

The spelling of 721706724 in words is "seven hundred twenty-one million, seven hundred six thousand, seven hundred twenty-four".