31366991 has 2 divisors, whose sum is σ = 31366992. Its totient is φ = 31366990.

The previous prime is 31366969. The next prime is 31366997. The reversal of 31366991 is 19966313.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 31366991 - 2¹⁸ = 31104847 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (31366997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 15683495 + 15683496.

It is an arithmetic number, because the mean of its divisors is an integer number (15683496).

Almost surely, 2^31366991 is an apocalyptic number.

31366991 is a deficient number, since it is larger than the sum of its proper divisors (1).

31366991 is an equidigital number, since it uses as much as digits as its factorization.

31366991 is an evil number, because the sum of its binary digits is even.

The product of its digits is 26244, while the sum is 38.

The square root of 31366991 is about 5600.6241616448. The cubic root of 31366991 is about 315.3728381133.

The spelling of 31366991 in words is "thirty-one million, three hundred sixty-six thousand, nine hundred ninety-one".