21599459 has 16 divisors (see below), whose sum is σ = 25631232. Its totient is φ = 17817408.

The previous prime is 21599449. The next prime is 21599471. The reversal of 21599459 is 95499512.

It is not a de Polignac number, because 21599459 - 2⁴ = 21599443 is a prime.

It is a Smith number, since the sum of its digits (44) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21599419) 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, 21482 + ... + 22464.

It is an arithmetic number, because the mean of its divisors is an integer number (1601952).

Almost surely, 2^21599459 is an apocalyptic number.

21599459 is a deficient number, since it is larger than the sum of its proper divisors (4031773).

21599459 is an equidigital number, since it uses as much as digits as its factorization.

21599459 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1106.

The product of its digits is 145800, while the sum is 44.

The square root of 21599459 is about 4647.5218127514. The cubic root of 21599459 is about 278.4930049052.

The spelling of 21599459 in words is "twenty-one million, five hundred ninety-nine thousand, four hundred fifty-nine".