31000891 has 2 divisors, whose sum is σ = 31000892. Its totient is φ = 31000890.

The previous prime is 31000889. The next prime is 31000897. The reversal of 31000891 is 19800013.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 31000891 - 2¹ = 31000889 is a prime.

It is a super-2 number, since 2×31000891² = 1922110485587762, which contains 22 as substring.

Together with 31000889, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (31000897) 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, 15500445 + 15500446.

It is an arithmetic number, because the mean of its divisors is an integer number (15500446).

Almost surely, 2^31000891 is an apocalyptic number.

31000891 is a deficient number, since it is larger than the sum of its proper divisors (1).

31000891 is an equidigital number, since it uses as much as digits as its factorization.

31000891 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 216, while the sum is 22.

The square root of 31000891 is about 5567.8443764171. The cubic root of 31000891 is about 314.1410748556.

The spelling of 31000891 in words is "thirty-one million, eight hundred ninety-one", and thus it is an aban number.