21579689 has 4 divisors (see below), whose sum is σ = 22275840. Its totient is φ = 20883540.

The previous prime is 21579673. The next prime is 21579707. The reversal of 21579689 is 98697512.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21579689 - 2⁴ = 21579673 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21579629) 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, 348029 + ... + 348090.

It is an arithmetic number, because the mean of its divisors is an integer number (5568960).

Almost surely, 2^21579689 is an apocalyptic number.

It is an amenable number.

21579689 is a deficient number, since it is larger than the sum of its proper divisors (696151).

21579689 is an equidigital number, since it uses as much as digits as its factorization.

21579689 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 696150.

The product of its digits is 272160, while the sum is 47.

The square root of 21579689 is about 4645.3943858407. The cubic root of 21579689 is about 278.4080106871.

The spelling of 21579689 in words is "twenty-one million, five hundred seventy-nine thousand, six hundred eighty-nine".