21328599 has 16 divisors (see below), whose sum is σ = 28892160. Its totient is φ = 13994400.

The previous prime is 21328597. The next prime is 21328603. The reversal of 21328599 is 99582312.

It is not a de Polignac number, because 21328599 - 2¹ = 21328597 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21328597) 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, 89122 + ... + 89360.

It is an arithmetic number, because the mean of its divisors is an integer number (1805760).

Almost surely, 2^21328599 is an apocalyptic number.

21328599 is a deficient number, since it is larger than the sum of its proper divisors (7563561).

21328599 is a wasteful number, since it uses less digits than its factorization.

21328599 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 590.

The product of its digits is 38880, while the sum is 39.

The square root of 21328599 is about 4618.2896184627. The cubic root of 21328599 is about 277.3239919512.

It can be divided in two parts, 2132 and 8599, that added together give a triangular number (10731 = T₁₄₆).

The spelling of 21328599 in words is "twenty-one million, three hundred twenty-eight thousand, five hundred ninety-nine".