91331621 has 4 divisors (see below), whose sum is σ = 91695744. Its totient is φ = 90967500.

The previous prime is 91331567. The next prime is 91331629. The reversal of 91331621 is 12613319.

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.

It is a cyclic number.

It is not a de Polignac number, because 91331621 - 2¹⁰ = 91330597 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 (91331629) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 181685 + ... + 182186.

It is an arithmetic number, because the mean of its divisors is an integer number (22923936).

Almost surely, 2^91331621 is an apocalyptic number.

It is an amenable number.

91331621 is a deficient number, since it is larger than the sum of its proper divisors (364123).

91331621 is a wasteful number, since it uses less digits than its factorization.

91331621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 364122.

The product of its digits is 972, while the sum is 26.

The square root of 91331621 is about 9556.7578707426. The cubic root of 91331621 is about 450.3398601302.

The spelling of 91331621 in words is "ninety-one million, three hundred thirty-one thousand, six hundred twenty-one".