31213999 has 2 divisors, whose sum is σ = 31214000. Its totient is φ = 31213998.

The previous prime is 31213981. The next prime is 31214021. The reversal of 31213999 is 99931213.

31213999 is nontrivially palindromic in base 7.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 31213999 - 2⁹ = 31213487 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31213939) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15606999 + 15607000.

It is an arithmetic number, because the mean of its divisors is an integer number (15607000).

Almost surely, 2^31213999 is an apocalyptic number.

31213999 is a deficient number, since it is larger than the sum of its proper divisors (1).

31213999 is an equidigital number, since it uses as much as digits as its factorization.

31213999 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 13122, while the sum is 37.

The square root of 31213999 is about 5586.9489884909. The cubic root of 31213999 is about 314.8592602151.

The spelling of 31213999 in words is "thirty-one million, two hundred thirteen thousand, nine hundred ninety-nine".