21979585 has 4 divisors (see below), whose sum is σ = 26375508. Its totient is φ = 17583664.

The previous prime is 21979571. The next prime is 21979603. The reversal of 21979585 is 58597912.

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

It can be written as a sum of positive squares in 2 ways, for example, as 15689521 + 6290064 = 3961^2 + 2508^2 .

It is a cyclic number.

It is not a de Polignac number, because 21979585 - 2⁵ = 21979553 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2197954 + ... + 2197963.

It is an arithmetic number, because the mean of its divisors is an integer number (6593877).

Almost surely, 2^21979585 is an apocalyptic number.

It is an amenable number.

21979585 is a deficient number, since it is larger than the sum of its proper divisors (4395923).

21979585 is an equidigital number, since it uses as much as digits as its factorization.

21979585 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4395922.

The product of its digits is 226800, while the sum is 46.

The square root of 21979585 is about 4688.2390084124. The cubic root of 21979585 is about 280.1172340713.

The spelling of 21979585 in words is "twenty-one million, nine hundred seventy-nine thousand, five hundred eighty-five".