31631081 has 2 divisors, whose sum is σ = 31631082. Its totient is φ = 31631080.

The previous prime is 31631077. The next prime is 31631087. The reversal of 31631081 is 18013613.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 25847056 + 5784025 = 5084^2 + 2405^2 .

It is an emirp because it is prime and its reverse (18013613) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31631081 - 2² = 31631077 is a prime.

It is a super-2 number, since 2×31631081² = 2001050570457122, 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 (31631087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15815540 + 15815541.

It is an arithmetic number, because the mean of its divisors is an integer number (15815541).

Almost surely, 2^31631081 is an apocalyptic number.

It is an amenable number.

31631081 is a deficient number, since it is larger than the sum of its proper divisors (1).

31631081 is an equidigital number, since it uses as much as digits as its factorization.

31631081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 432, while the sum is 23.

The square root of 31631081 is about 5624.1515804608. The cubic root of 31631081 is about 316.2554449218.

Adding to 31631081 its reverse (18013613), we get a palindrome (49644694).

The spelling of 31631081 in words is "thirty-one million, six hundred thirty-one thousand, eighty-one".