91159921 has 4 divisors (see below), whose sum is σ = 92099812. Its totient is φ = 90220032.

The previous prime is 91159919. The next prime is 91159949. The reversal of 91159921 is 12995119.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12995119 = 67 ⋅193957.

It can be written as a sum of positive squares in 2 ways, for example, as 61402896 + 29757025 = 7836^2 + 5455^2 .

It is a cyclic number.

It is not a de Polignac number, because 91159921 - 2¹ = 91159919 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (91159951) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 469800 + ... + 469993.

It is an arithmetic number, because the mean of its divisors is an integer number (23024953).

Almost surely, 2^91159921 is an apocalyptic number.

It is an amenable number.

91159921 is a deficient number, since it is larger than the sum of its proper divisors (939891).

91159921 is an equidigital number, since it uses as much as digits as its factorization.

91159921 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 939890.

The product of its digits is 7290, while the sum is 37.

The square root of 91159921 is about 9547.7704727334. The cubic root of 91159921 is about 450.0574757862.

The spelling of 91159921 in words is "ninety-one million, one hundred fifty-nine thousand, nine hundred twenty-one".