31121491 has 2 divisors, whose sum is σ = 31121492. Its totient is φ = 31121490.

The previous prime is 31121483. The next prime is 31121527. The reversal of 31121491 is 19412113.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 31121491 - 2³ = 31121483 is a prime.

It is not a weakly prime, because it can be changed into another prime (31121401) 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, 15560745 + 15560746.

It is an arithmetic number, because the mean of its divisors is an integer number (15560746).

Almost surely, 2^31121491 is an apocalyptic number.

31121491 is a deficient number, since it is larger than the sum of its proper divisors (1).

31121491 is an equidigital number, since it uses as much as digits as its factorization.

31121491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 216, while the sum is 22.

The square root of 31121491 is about 5578.6639081414. The cubic root of 31121491 is about 314.5479060885.

The spelling of 31121491 in words is "thirty-one million, one hundred twenty-one thousand, four hundred ninety-one".