21437579 has 4 divisors (see below), whose sum is σ = 21457176. Its totient is φ = 21417984.

The previous prime is 21437573. The next prime is 21437617. The reversal of 21437579 is 97573412.

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 21437579 - 2²⁰ = 20389003 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21437573) 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, 8054 + ... + 10379.

It is an arithmetic number, because the mean of its divisors is an integer number (5364294).

Almost surely, 2^21437579 is an apocalyptic number.

21437579 is a deficient number, since it is larger than the sum of its proper divisors (19597).

21437579 is a wasteful number, since it uses less digits than its factorization.

21437579 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19596.

The product of its digits is 52920, while the sum is 38.

The square root of 21437579 is about 4630.0733255533. The cubic root of 21437579 is about 277.7955253312.

The spelling of 21437579 in words is "twenty-one million, four hundred thirty-seven thousand, five hundred seventy-nine".