31681609 has 2 divisors, whose sum is σ = 31681610. Its totient is φ = 31681608.

The previous prime is 31681589. The next prime is 31681621. The reversal of 31681609 is 90618613.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 31674384 + 7225 = 5628^2 + 85^2 .

It is a cyclic number.

It is not a de Polignac number, because 31681609 - 2¹⁷ = 31550537 is a prime.

It is equal to p_1955374 and since 31681609 and 1955374 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 (31688609) 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, 15840804 + 15840805.

It is an arithmetic number, because the mean of its divisors is an integer number (15840805).

Almost surely, 2^31681609 is an apocalyptic number.

It is an amenable number.

31681609 is a deficient number, since it is larger than the sum of its proper divisors (1).

31681609 is an equidigital number, since it uses as much as digits as its factorization.

31681609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7776, while the sum is 34.

The square root of 31681609 is about 5628.6418432869. The cubic root of 31681609 is about 316.4237525208.

The spelling of 31681609 in words is "thirty-one million, six hundred eighty-one thousand, six hundred nine".