21945579 has 8 divisors (see below), whose sum is σ = 29424960. Its totient is φ = 14548296.

The previous prime is 21945577. The next prime is 21945587. The reversal of 21945579 is 97554912.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21945579 - 2¹ = 21945577 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21945579.

It is not an unprimeable number, because it can be changed into a prime (21945577) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19897 + ... + 20970.

It is an arithmetic number, because the mean of its divisors is an integer number (3678120).

Almost surely, 2^21945579 is an apocalyptic number.

21945579 is a deficient number, since it is larger than the sum of its proper divisors (7479381).

21945579 is a wasteful number, since it uses less digits than its factorization.

21945579 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41049.

The product of its digits is 113400, while the sum is 42.

The square root of 21945579 is about 4684.6108696454. The cubic root of 21945579 is about 279.9726971677.

The spelling of 21945579 in words is "twenty-one million, nine hundred forty-five thousand, five hundred seventy-nine".