91221102021 has 16 divisors (see below), whose sum is σ = 139723816064. Its totient is φ = 51856257024.

The previous prime is 91221102013. The next prime is 91221102031. The reversal of 91221102021 is 12020112219.

It is not a de Polignac number, because 91221102021 - 2³ = 91221102013 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91221102031) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11249476 + ... + 11257581.

It is an arithmetic number, because the mean of its divisors is an integer number (8732738504).

Almost surely, 2^91221102021 is an apocalyptic number.

It is an amenable number.

91221102021 is a deficient number, since it is larger than the sum of its proper divisors (48502714043).

91221102021 is a wasteful number, since it uses less digits than its factorization.

91221102021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22507260.

The product of its (nonzero) digits is 144, while the sum is 21.

The spelling of 91221102021 in words is "ninety-one billion, two hundred twenty-one million, one hundred two thousand, twenty-one".