31312213 has 4 divisors (see below), whose sum is σ = 32040448. Its totient is φ = 30583980.

The previous prime is 31312163. The next prime is 31312217. The reversal of 31312213 is 31221313.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 31312213 - 2⁹ = 31311701 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31312217) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 364053 + ... + 364138.

It is an arithmetic number, because the mean of its divisors is an integer number (8010112).

Almost surely, 2^31312213 is an apocalyptic number.

It is an amenable number.

31312213 is a deficient number, since it is larger than the sum of its proper divisors (728235).

31312213 is an equidigital number, since it uses as much as digits as its factorization.

31312213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 728234.

The product of its digits is 108, while the sum is 16.

The square root of 31312213 is about 5595.7316769123. The cubic root of 31312213 is about 315.1891465005.

Adding to 31312213 its reverse (31221313), we get a palindrome (62533526).

The spelling of 31312213 in words is "thirty-one million, three hundred twelve thousand, two hundred thirteen".