91564021 has 4 divisors (see below), whose sum is σ = 96383200. Its totient is φ = 86744844.

The previous prime is 91563949. The next prime is 91564043. The reversal of 91564021 is 12046519.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 12046519 = 1907 ⋅6317.

It is a cyclic number.

It is not a de Polignac number, because 91564021 - 2⁷ = 91563893 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91564051) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2409561 + ... + 2409598.

It is an arithmetic number, because the mean of its divisors is an integer number (24095800).

Almost surely, 2^91564021 is an apocalyptic number.

It is an amenable number.

91564021 is a deficient number, since it is larger than the sum of its proper divisors (4819179).

91564021 is a wasteful number, since it uses less digits than its factorization.

91564021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4819178.

The product of its (nonzero) digits is 2160, while the sum is 28.

The square root of 91564021 is about 9568.9090809768. The cubic root of 91564021 is about 450.7215108547.

The spelling of 91564021 in words is "ninety-one million, five hundred sixty-four thousand, twenty-one".