21979573 has 16 divisors (see below), whose sum is σ = 27624960. Its totient is φ = 16988400.

The previous prime is 21979571. The next prime is 21979603. The reversal of 21979573 is 37597912.

It is not a de Polignac number, because 21979573 - 2¹ = 21979571 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21979571) 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, 8998 + ... + 11176.

It is an arithmetic number, because the mean of its divisors is an integer number (1726560).

Almost surely, 2^21979573 is an apocalyptic number.

It is an amenable number.

21979573 is a deficient number, since it is larger than the sum of its proper divisors (5645387).

21979573 is a wasteful number, since it uses less digits than its factorization.

21979573 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2328.

The product of its digits is 119070, while the sum is 43.

The square root of 21979573 is about 4688.2377286140. The cubic root of 21979573 is about 280.1171830936.

The spelling of 21979573 in words is "twenty-one million, nine hundred seventy-nine thousand, five hundred seventy-three".