90631991 has 2 divisors, whose sum is σ = 90631992. Its totient is φ = 90631990.

The previous prime is 90631987. The next prime is 90631999. The reversal of 90631991 is 19913609.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 90631991 - 2² = 90631987 is a prime.

It is a super-3 number, since 3×90631991³ (a number of 25 digits) contains 333 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (90631999) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45315995 + 45315996.

It is an arithmetic number, because the mean of its divisors is an integer number (45315996).

Almost surely, 2^90631991 is an apocalyptic number.

90631991 is a deficient number, since it is larger than the sum of its proper divisors (1).

90631991 is an equidigital number, since it uses as much as digits as its factorization.

90631991 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 13122, while the sum is 38.

The square root of 90631991 is about 9520.0835605576. The cubic root of 90631991 is about 449.1869945965.

The spelling of 90631991 in words is "ninety million, six hundred thirty-one thousand, nine hundred ninety-one".