31985491 has 2 divisors, whose sum is σ = 31985492. Its totient is φ = 31985490.

The previous prime is 31985489. The next prime is 31985537. The reversal of 31985491 is 19458913.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 31985491 - 2¹ = 31985489 is a prime.

It is a super-2 number, since 2×31985491² = 2046143269022162, which contains 22 as substring.

Together with 31985489, it forms a pair of twin primes.

It is equal to p_1972957 and since 31985491 and 1972957 have the same sum of digits, it is a Honaker prime.

It is not a weakly prime, because it can be changed into another prime (31985431) 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, 15992745 + 15992746.

It is an arithmetic number, because the mean of its divisors is an integer number (15992746).

Almost surely, 2^31985491 is an apocalyptic number.

31985491 is a deficient number, since it is larger than the sum of its proper divisors (1).

31985491 is an equidigital number, since it uses as much as digits as its factorization.

31985491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 38880, while the sum is 40.

The square root of 31985491 is about 5655.5716775583. The cubic root of 31985491 is about 317.4322206361.

The spelling of 31985491 in words is "thirty-one million, nine hundred eighty-five thousand, four hundred ninety-one".