721685231 has 2 divisors, whose sum is σ = 721685232. Its totient is φ = 721685230.

The previous prime is 721685183. The next prime is 721685257. The reversal of 721685231 is 132586127.

It is a happy number.

It is a strong prime.

It is an emirp because it is prime and its reverse (132586127) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 721685231 - 2¹⁴ = 721668847 is a prime.

It is a super-2 number, since 2×721685231² = 1041659145287046722, which contains 22 as substring.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 721685191 and 721685200.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721685131) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360842615 + 360842616.

It is an arithmetic number, because the mean of its divisors is an integer number (360842616).

Almost surely, 2^721685231 is an apocalyptic number.

721685231 is a deficient number, since it is larger than the sum of its proper divisors (1).

721685231 is an equidigital number, since it uses as much as digits as its factorization.

721685231 is an evil number, because the sum of its binary digits is even.

The product of its digits is 20160, while the sum is 35.

The square root of 721685231 is about 26864.1998019669. The cubic root of 721685231 is about 896.9796824251.

The spelling of 721685231 in words is "seven hundred twenty-one million, six hundred eighty-five thousand, two hundred thirty-one".