31191689 has 2 divisors, whose sum is σ = 31191690. Its totient is φ = 31191688.

The previous prime is 31191683. The next prime is 31191731. The reversal of 31191689 is 98619113.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 30614089 + 577600 = 5533^2 + 760^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31191689 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (31191683) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15595844 + 15595845.

It is an arithmetic number, because the mean of its divisors is an integer number (15595845).

Almost surely, 2^31191689 is an apocalyptic number.

It is an amenable number.

31191689 is a deficient number, since it is larger than the sum of its proper divisors (1).

31191689 is an equidigital number, since it uses as much as digits as its factorization.

31191689 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 11664, while the sum is 38.

The square root of 31191689 is about 5584.9520141179. The cubic root of 31191689 is about 314.7842278091.

The spelling of 31191689 in words is "thirty-one million, one hundred ninety-one thousand, six hundred eighty-nine".