21089599 has 4 divisors (see below), whose sum is σ = 21178080. Its totient is φ = 21001120.

The previous prime is 21089581. The next prime is 21089611. The reversal of 21089599 is 99598012.

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 21089599 - 2⁵ = 21089567 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 (21089569) 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, 43882 + ... + 44359.

It is an arithmetic number, because the mean of its divisors is an integer number (5294520).

Almost surely, 2^21089599 is an apocalyptic number.

21089599 is a deficient number, since it is larger than the sum of its proper divisors (88481).

21089599 is an equidigital number, since it uses as much as digits as its factorization.

21089599 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88480.

The product of its (nonzero) digits is 58320, while the sum is 43.

The square root of 21089599 is about 4592.3413418430. The cubic root of 21089599 is about 276.2842368656.

The spelling of 21089599 in words is "twenty-one million, eighty-nine thousand, five hundred ninety-nine".