31331081 has 2 divisors, whose sum is σ = 31331082. Its totient is φ = 31331080.

The previous prime is 31331071. The next prime is 31331087. The reversal of 31331081 is 18013313.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26988025 + 4343056 = 5195^2 + 2084^2 .

It is an emirp because it is prime and its reverse (18013313) is a distict prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31331081 is a prime.

It is a super-2 number, since 2×31331081² = 1963273273257122, which contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (31331087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15665540 + 15665541.

It is an arithmetic number, because the mean of its divisors is an integer number (15665541).

Almost surely, 2^31331081 is an apocalyptic number.

It is an amenable number.

31331081 is a deficient number, since it is larger than the sum of its proper divisors (1).

31331081 is an equidigital number, since it uses as much as digits as its factorization.

31331081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 31331081 is about 5597.4173508860. The cubic root of 31331081 is about 315.2524423005.

Adding to 31331081 its reverse (18013313), we get a palindrome (49344394).

The spelling of 31331081 in words is "thirty-one million, three hundred thirty-one thousand, eighty-one".