91537591 has 2 divisors, whose sum is σ = 91537592. Its totient is φ = 91537590.

The previous prime is 91537577. The next prime is 91537597. The reversal of 91537591 is 19573519.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 91537591 - 2¹⁵ = 91504823 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (91537597) by changing a digit.

It is an upside-down number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45768795 + 45768796.

It is an arithmetic number, because the mean of its divisors is an integer number (45768796).

Almost surely, 2^91537591 is an apocalyptic number.

91537591 is a deficient number, since it is larger than the sum of its proper divisors (1).

91537591 is an equidigital number, since it uses as much as digits as its factorization.

91537591 is an evil number, because the sum of its binary digits is even.

The product of its digits is 42525, while the sum is 40.

The square root of 91537591 is about 9567.5279461311. The cubic root of 91537591 is about 450.6781396856.

It can be divided in two parts, 9 and 1537591, that added together give a square (1537600 = 1240²).

The spelling of 91537591 in words is "ninety-one million, five hundred thirty-seven thousand, five hundred ninety-one".