21265579 has 4 divisors (see below), whose sum is σ = 22384840. Its totient is φ = 20146320.

The previous prime is 21265577. The next prime is 21265603. The reversal of 21265579 is 97556212.

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 21265579 - 2¹ = 21265577 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21265577) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 559602 + ... + 559639.

It is an arithmetic number, because the mean of its divisors is an integer number (5596210).

Almost surely, 2^21265579 is an apocalyptic number.

21265579 is a deficient number, since it is larger than the sum of its proper divisors (1119261).

21265579 is a wasteful number, since it uses less digits than its factorization.

21265579 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1119260.

The product of its digits is 37800, while the sum is 37.

The square root of 21265579 is about 4611.4616988543. The cubic root of 21265579 is about 277.0505844097.

The spelling of 21265579 in words is "twenty-one million, two hundred sixty-five thousand, five hundred seventy-nine".