31893991 has 2 divisors, whose sum is σ = 31893992. Its totient is φ = 31893990.

The previous prime is 31893977. The next prime is 31894001. The reversal of 31893991 is 19939813.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 31893991 - 2¹¹ = 31891943 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31893971) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15946995 + 15946996.

It is an arithmetic number, because the mean of its divisors is an integer number (15946996).

Almost surely, 2^31893991 is an apocalyptic number.

31893991 is a deficient number, since it is larger than the sum of its proper divisors (1).

31893991 is an equidigital number, since it uses as much as digits as its factorization.

31893991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 52488, while the sum is 43.

The square root of 31893991 is about 5647.4765161088. The cubic root of 31893991 is about 317.1292417176.

The spelling of 31893991 in words is "thirty-one million, eight hundred ninety-three thousand, nine hundred ninety-one".