31581961 has 2 divisors, whose sum is σ = 31581962. Its totient is φ = 31581960.

The previous prime is 31581947. The next prime is 31581973. The reversal of 31581961 is 16918513.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 22467600 + 9114361 = 4740^2 + 3019^2 .

It is a cyclic number.

It is not a de Polignac number, because 31581961 - 2⁹ = 31581449 is a prime.

It is not a weakly prime, because it can be changed into another prime (31581911) 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, 15790980 + 15790981.

It is an arithmetic number, because the mean of its divisors is an integer number (15790981).

Almost surely, 2^31581961 is an apocalyptic number.

It is an amenable number.

31581961 is a deficient number, since it is larger than the sum of its proper divisors (1).

31581961 is an equidigital number, since it uses as much as digits as its factorization.

31581961 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 6480, while the sum is 34.

The square root of 31581961 is about 5619.7830029281. The cubic root of 31581961 is about 316.0916554350.

The spelling of 31581961 in words is "thirty-one million, five hundred eighty-one thousand, nine hundred sixty-one".