31331609 has 2 divisors, whose sum is σ = 31331610. Its totient is φ = 31331608.

The previous prime is 31331603. The next prime is 31331611. The reversal of 31331609 is 90613313.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 26491609 + 4840000 = 5147^2 + 2200^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31331609 is a prime.

It is a Sophie Germain prime.

Together with 31331611, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (31331603) 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, 15665804 + 15665805.

It is an arithmetic number, because the mean of its divisors is an integer number (15665805).

Almost surely, 2^31331609 is an apocalyptic number.

It is an amenable number.

31331609 is a deficient number, since it is larger than the sum of its proper divisors (1).

31331609 is an equidigital number, since it uses as much as digits as its factorization.

31331609 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1458, while the sum is 26.

The square root of 31331609 is about 5597.4645152962. The cubic root of 31331609 is about 315.2542131975.

The spelling of 31331609 in words is "thirty-one million, three hundred thirty-one thousand, six hundred nine".