31390231 has 4 divisors (see below), whose sum is σ = 31616200. Its totient is φ = 31164264.

The previous prime is 31390213. The next prime is 31390253. The reversal of 31390231 is 13209313.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 31390231 - 2⁵ = 31390199 is a prime.

It is a super-2 number, since 2×31390231² = 1970693204466722, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (31396231) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 112776 + ... + 113053.

It is an arithmetic number, because the mean of its divisors is an integer number (7904050).

Almost surely, 2^31390231 is an apocalyptic number.

31390231 is a deficient number, since it is larger than the sum of its proper divisors (225969).

31390231 is a wasteful number, since it uses less digits than its factorization.

31390231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 225968.

The product of its (nonzero) digits is 486, while the sum is 22.

The square root of 31390231 is about 5602.6985462364. The cubic root of 31390231 is about 315.4507061222.

Adding to 31390231 its reverse (13209313), we get a palindrome (44599544).

The spelling of 31390231 in words is "thirty-one million, three hundred ninety thousand, two hundred thirty-one".