31312081 has 2 divisors, whose sum is σ = 31312082. Its totient is φ = 31312080.

The previous prime is 31312051. The next prime is 31312087. The reversal of 31312081 is 18021313.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 30902481 + 409600 = 5559^2 + 640^2 .

It is a cyclic number.

It is not a de Polignac number, because 31312081 - 2⁵ = 31312049 is a prime.

It is a super-2 number, since 2×31312081² = 1960892833101122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (31312087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15656040 + 15656041.

It is an arithmetic number, because the mean of its divisors is an integer number (15656041).

Almost surely, 2^31312081 is an apocalyptic number.

It is an amenable number.

31312081 is a deficient number, since it is larger than the sum of its proper divisors (1).

31312081 is an equidigital number, since it uses as much as digits as its factorization.

31312081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 31312081 is about 5595.7198821957. The cubic root of 31312081 is about 315.1887035953.

Adding to 31312081 its reverse (18021313), we get a palindrome (49333394).

The spelling of 31312081 in words is "thirty-one million, three hundred twelve thousand, eighty-one".