91621599 has 4 divisors (see below), whose sum is σ = 122162136. Its totient is φ = 61081064.

The previous prime is 91621571. The next prime is 91621603. The reversal of 91621599 is 99512619.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 91621599 - 2⁵ = 91621567 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 91621599.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (91621099) 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, 15270264 + ... + 15270269.

It is an arithmetic number, because the mean of its divisors is an integer number (30540534).

Almost surely, 2^91621599 is an apocalyptic number.

91621599 is a deficient number, since it is larger than the sum of its proper divisors (30540537).

91621599 is a wasteful number, since it uses less digits than its factorization.

91621599 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 30540536.

The product of its digits is 43740, while the sum is 42.

The square root of 91621599 is about 9571.9172060774. The cubic root of 91621599 is about 450.8159664609.

The spelling of 91621599 in words is "ninety-one million, six hundred twenty-one thousand, five hundred ninety-nine".