21853239 has 4 divisors (see below), whose sum is σ = 29137656. Its totient is φ = 14568824.

The previous prime is 21853231. The next prime is 21853309. The reversal of 21853239 is 93235812.

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 21853239 - 2³ = 21853231 is a prime.

It is a super-2 number, since 2×21853239² = 955128109582242, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21853231) 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, 3642204 + ... + 3642209.

It is an arithmetic number, because the mean of its divisors is an integer number (7284414).

Almost surely, 2^21853239 is an apocalyptic number.

21853239 is a deficient number, since it is larger than the sum of its proper divisors (7284417).

21853239 is an equidigital number, since it uses as much as digits as its factorization.

21853239 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7284416.

The product of its digits is 12960, while the sum is 33.

The square root of 21853239 is about 4674.7448058691. The cubic root of 21853239 is about 279.5794665038.

The spelling of 21853239 in words is "twenty-one million, eight hundred fifty-three thousand, two hundred thirty-nine".