91120021 has 4 divisors (see below), whose sum is σ = 91144044. Its totient is φ = 91096000.

The previous prime is 91119979. The next prime is 91120027. The reversal of 91120021 is 12002119.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 50339025 + 40780996 = 7095^2 + 6386^2 .

It is a cyclic number.

It is not a de Polignac number, because 91120021 - 2²⁵ = 57565589 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 91119977 and 91120004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91120027) 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, 4930 + ... + 14371.

It is an arithmetic number, because the mean of its divisors is an integer number (22786011).

Almost surely, 2^91120021 is an apocalyptic number.

It is an amenable number.

91120021 is a deficient number, since it is larger than the sum of its proper divisors (24023).

91120021 is a wasteful number, since it uses less digits than its factorization.

91120021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24022.

The product of its (nonzero) digits is 36, while the sum is 16.

The square root of 91120021 is about 9545.6807509994. The cubic root of 91120021 is about 449.9918039659.

The spelling of 91120021 in words is "ninety-one million, one hundred twenty thousand, twenty-one".