91937221 has 4 divisors (see below), whose sum is σ = 95107500. Its totient is φ = 88766944.

The previous prime is 91937203. The next prime is 91937231. The reversal of 91937221 is 12273919.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12273919 = 7 ⋅1753417.

It can be written as a sum of positive squares in 2 ways, for example, as 77686596 + 14250625 = 8814^2 + 3775^2 .

It is a cyclic number.

It is not a de Polignac number, because 91937221 - 2⁵ = 91937189 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 (91937201) 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, 1585096 + ... + 1585153.

It is an arithmetic number, because the mean of its divisors is an integer number (23776875).

Almost surely, 2^91937221 is an apocalyptic number.

It is an amenable number.

91937221 is a deficient number, since it is larger than the sum of its proper divisors (3170279).

91937221 is a wasteful number, since it uses less digits than its factorization.

91937221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3170278.

The product of its digits is 6804, while the sum is 34.

The square root of 91937221 is about 9588.3899065484. The cubic root of 91937221 is about 451.3330365425. Note that the first 3 decimals are identical.

The spelling of 91937221 in words is "ninety-one million, nine hundred thirty-seven thousand, two hundred twenty-one".