31330891 has 2 divisors, whose sum is σ = 31330892. Its totient is φ = 31330890.

The previous prime is 31330889. The next prime is 31330909. The reversal of 31330891 is 19803313.

It is a weak prime.

It is an emirp because it is prime and its reverse (19803313) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 31330891 - 2¹ = 31330889 is a prime.

Together with 31330889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (31330841) 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, 15665445 + 15665446.

It is an arithmetic number, because the mean of its divisors is an integer number (15665446).

Almost surely, 2^31330891 is an apocalyptic number.

31330891 is a deficient number, since it is larger than the sum of its proper divisors (1).

31330891 is an equidigital number, since it uses as much as digits as its factorization.

31330891 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 31330891 is about 5597.4003787473. The cubic root of 31330891 is about 315.2518050410.

The spelling of 31330891 in words is "thirty-one million, three hundred thirty thousand, eight hundred ninety-one".