91551631 has 2 divisors, whose sum is σ = 91551632. Its totient is φ = 91551630.

The previous prime is 91551623. The next prime is 91551679. The reversal of 91551631 is 13615519.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 91551631 - 2³ = 91551623 is a prime.

It is a super-2 number, since 2×91551631² = 16763402277520322, which contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 91551593 and 91551602.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91551931) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45775815 + 45775816.

It is an arithmetic number, because the mean of its divisors is an integer number (45775816).

Almost surely, 2^91551631 is an apocalyptic number.

91551631 is the 6052-nd centered pentagonal number.

91551631 is a deficient number, since it is larger than the sum of its proper divisors (1).

91551631 is an equidigital number, since it uses as much as digits as its factorization.

91551631 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4050, while the sum is 31.

The square root of 91551631 is about 9568.2616498505. The cubic root of 91551631 is about 450.7011801201.

The spelling of 91551631 in words is "ninety-one million, five hundred fifty-one thousand, six hundred thirty-one".