21911579 has 4 divisors (see below), whose sum is σ = 23064840. Its totient is φ = 20758320.

The previous prime is 21911573. The next prime is 21911581. The reversal of 21911579 is 97511912.

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 21911579 - 2¹⁶ = 21846043 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21911573) 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, 576602 + ... + 576639.

It is an arithmetic number, because the mean of its divisors is an integer number (5766210).

Almost surely, 2^21911579 is an apocalyptic number.

21911579 is a deficient number, since it is larger than the sum of its proper divisors (1153261).

21911579 is a wasteful number, since it uses less digits than its factorization.

21911579 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1153260.

The product of its digits is 5670, while the sum is 35.

The square root of 21911579 is about 4680.9805596691. The cubic root of 21911579 is about 279.8280364160.

The spelling of 21911579 in words is "twenty-one million, nine hundred eleven thousand, five hundred seventy-nine".