91639221 has 8 divisors (see below), whose sum is σ = 123658080. Its totient is φ = 60356592.

The previous prime is 91639189. The next prime is 91639241. The reversal of 91639221 is 12293619.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 91639221 - 2⁵ = 91639189 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91639241) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 183766 + ... + 184263.

It is an arithmetic number, because the mean of its divisors is an integer number (15457260).

Almost surely, 2^91639221 is an apocalyptic number.

It is an amenable number.

91639221 is a deficient number, since it is larger than the sum of its proper divisors (32018859).

91639221 is a wasteful number, since it uses less digits than its factorization.

91639221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 368115.

The product of its digits is 5832, while the sum is 33.

The square root of 91639221 is about 9572.8376670661. The cubic root of 91639221 is about 450.8448671051.

The spelling of 91639221 in words is "ninety-one million, six hundred thirty-nine thousand, two hundred twenty-one".