21368579 has 4 divisors (see below), whose sum is σ = 22057920. Its totient is φ = 20679240.

The previous prime is 21368569. The next prime is 21368591. The reversal of 21368579 is 97586312.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21368579 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21368539) 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, 344624 + ... + 344685.

It is an arithmetic number, because the mean of its divisors is an integer number (5514480).

Almost surely, 2^21368579 is an apocalyptic number.

21368579 is a deficient number, since it is larger than the sum of its proper divisors (689341).

21368579 is an equidigital number, since it uses as much as digits as its factorization.

21368579 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 689340.

The product of its digits is 90720, while the sum is 41.

The square root of 21368579 is about 4622.6160342386. The cubic root of 21368579 is about 277.4971630801.

The spelling of 21368579 in words is "twenty-one million, three hundred sixty-eight thousand, five hundred seventy-nine".