721312231 has 2 divisors, whose sum is σ = 721312232. Its totient is φ = 721312230.

The previous prime is 721312087. The next prime is 721312237. The reversal of 721312231 is 132213127.

It is a happy number.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 721312231 - 2⁹ = 721311719 is a prime.

It is a super-2 number, since 2×721312231² = 1040582669180394722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (721312237) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 360656115 + 360656116.

It is an arithmetic number, because the mean of its divisors is an integer number (360656116).

Almost surely, 2^721312231 is an apocalyptic number.

721312231 is a deficient number, since it is larger than the sum of its proper divisors (1).

721312231 is an equidigital number, since it uses as much as digits as its factorization.

721312231 is an evil number, because the sum of its binary digits is even.

The product of its digits is 504, while the sum is 22.

The square root of 721312231 is about 26857.2565799264. The cubic root of 721312231 is about 896.8251223922.

Adding to 721312231 its reverse (132213127), we get a palindrome (853525358).

The spelling of 721312231 in words is "seven hundred twenty-one million, three hundred twelve thousand, two hundred thirty-one".