721317231 has 10 divisors (see below), whose sum is σ = 1077523392. Its totient is φ = 480878100.

The previous prime is 721317229. The next prime is 721317239. The reversal of 721317231 is 132713127.

It is not a de Polignac number, because 721317231 - 2¹ = 721317229 is a prime.

It is a super-2 number, since 2×721317231² = 1040597095475014722, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a junction number, because it is equal to n+sod(n) for n = 721317195 and 721317204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721317239) by changing a digit.

It is a polite number, since it can be written in 9 ways as a sum of consecutive naturals, for example, 4452495 + ... + 4452656.

Almost surely, 2^721317231 is an apocalyptic number.

721317231 is a deficient number, since it is larger than the sum of its proper divisors (356206161).

721317231 is an equidigital number, since it uses as much as digits as its factorization.

721317231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8905163 (or 8905154 counting only the distinct ones).

The product of its digits is 1764, while the sum is 27.

The square root of 721317231 is about 26857.3496644773. The cubic root of 721317231 is about 896.8271945949.

The spelling of 721317231 in words is "seven hundred twenty-one million, three hundred seventeen thousand, two hundred thirty-one".