31990031 has 2 divisors, whose sum is σ = 31990032. Its totient is φ = 31990030.

The previous prime is 31990027. The next prime is 31990043. The reversal of 31990031 is 13009913.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 31990031 - 2² = 31990027 is a prime.

It is a super-2 number, since 2×31990031² = 2046724166761922, which contains 22 as substring.

It is equal to p_1973222 and since 31990031 and 1973222 have the same sum of digits, it is a Honaker prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31990051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15995015 + 15995016.

It is an arithmetic number, because the mean of its divisors is an integer number (15995016).

Almost surely, 2^31990031 is an apocalyptic number.

31990031 is a deficient number, since it is larger than the sum of its proper divisors (1).

31990031 is an equidigital number, since it uses as much as digits as its factorization.

31990031 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 729, while the sum is 26.

The square root of 31990031 is about 5655.9730374181. The cubic root of 31990031 is about 317.4472386339.

Adding to 31990031 its reverse (13009913), we get a palindrome (44999944).

The spelling of 31990031 in words is "thirty-one million, nine hundred ninety thousand, thirty-one".