31661491 has 2 divisors, whose sum is σ = 31661492. Its totient is φ = 31661490.

The previous prime is 31661477. The next prime is 31661507. The reversal of 31661491 is 19416613.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 31661491 - 2¹⁷ = 31530419 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (31661401) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15830745 + 15830746.

It is an arithmetic number, because the mean of its divisors is an integer number (15830746).

Almost surely, 2^31661491 is an apocalyptic number.

31661491 is a deficient number, since it is larger than the sum of its proper divisors (1).

31661491 is an equidigital number, since it uses as much as digits as its factorization.

31661491 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3888, while the sum is 31.

The square root of 31661491 is about 5626.8544498681. The cubic root of 31661491 is about 316.3567613844.

The spelling of 31661491 in words is "thirty-one million, six hundred sixty-one thousand, four hundred ninety-one".