31321691 has 2 divisors, whose sum is σ = 31321692. Its totient is φ = 31321690.

The previous prime is 31321651. The next prime is 31321727. The reversal of 31321691 is 19612313.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-31321691 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 31321691.

It is not a weakly prime, because it can be changed into another prime (31321651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15660845 + 15660846.

It is an arithmetic number, because the mean of its divisors is an integer number (15660846).

Almost surely, 2^31321691 is an apocalyptic number.

31321691 is a deficient number, since it is larger than the sum of its proper divisors (1).

31321691 is an equidigital number, since it uses as much as digits as its factorization.

31321691 is an evil number, because the sum of its binary digits is even.

The product of its digits is 972, while the sum is 26.

The square root of 31321691 is about 5596.5785083388. The cubic root of 31321691 is about 315.2209451830.

The spelling of 31321691 in words is "thirty-one million, three hundred twenty-one thousand, six hundred ninety-one".