31331213 has 4 divisors (see below), whose sum is σ = 31442208. Its totient is φ = 31220220.

The previous prime is 31331207. The next prime is 31331231. The reversal of 31331213 is 31213313.

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, and also an emirpimes, since its reverse is a distinct semiprime: 31213313 = 43 ⋅725891.

It is a cyclic number.

It is not a de Polignac number, because 31331213 - 2⁴ = 31331197 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 31331191 and 31331200.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31331203) 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, 55073 + ... + 55638.

It is an arithmetic number, because the mean of its divisors is an integer number (7860552).

Almost surely, 2^31331213 is an apocalyptic number.

It is an amenable number.

31331213 is a deficient number, since it is larger than the sum of its proper divisors (110995).

31331213 is a wasteful number, since it uses less digits than its factorization.

31331213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 110994.

The product of its digits is 162, while the sum is 17.

The square root of 31331213 is about 5597.4291420258. The cubic root of 31331213 is about 315.2528850266.

Adding to 31331213 its reverse (31213313), we get a palindrome (62544526).

The spelling of 31331213 in words is "thirty-one million, three hundred thirty-one thousand, two hundred thirteen".