91564591 has 4 divisors (see below), whose sum is σ = 96383800. Its totient is φ = 86745384.

The previous prime is 91564589. The next prime is 91564609. The reversal of 91564591 is 19546519.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 19546519 = 409 ⋅47791.

It is a cyclic number.

It is not a de Polignac number, because 91564591 - 2¹ = 91564589 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91564391) by changing a digit.

It is an upside-down number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2409576 + ... + 2409613.

It is an arithmetic number, because the mean of its divisors is an integer number (24095950).

Almost surely, 2^91564591 is an apocalyptic number.

91564591 is a deficient number, since it is larger than the sum of its proper divisors (4819209).

91564591 is a wasteful number, since it uses less digits than its factorization.

91564591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4819208.

The product of its digits is 48600, while the sum is 40.

The square root of 91564591 is about 9568.9388648899. The cubic root of 91564591 is about 450.7224461228.

The spelling of 91564591 in words is "ninety-one million, five hundred sixty-four thousand, five hundred ninety-one".