3131981 has 2 divisors, whose sum is σ = 3131982. Its totient is φ = 3131980.

The previous prime is 3131977. The next prime is 3131983. The reversal of 3131981 is 1891313.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 3118756 + 13225 = 1766^2 + 115^2 .

It is a cyclic number.

It is not a de Polignac number, because 3131981 - 2² = 3131977 is a prime.

It is a super-2 number, since 2×3131981² = 19618609968722, which contains 22 as substring.

It is a Sophie Germain prime.

Together with 3131983, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 3131981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (3131983) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1565990 + 1565991.

It is an arithmetic number, because the mean of its divisors is an integer number (1565991).

Almost surely, 2^3131981 is an apocalyptic number.

It is an amenable number.

3131981 is a deficient number, since it is larger than the sum of its proper divisors (1).

3131981 is an equidigital number, since it uses as much as digits as its factorization.

3131981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 648, while the sum is 26.

The square root of 3131981 is about 1769.7403764394. The cubic root of 3131981 is about 146.3096729728.

The spelling of 3131981 in words is "three million, one hundred thirty-one thousand, nine hundred eighty-one".