21916239 has 4 divisors (see below), whose sum is σ = 29221656. Its totient is φ = 14610824.

The previous prime is 21916231. The next prime is 21916243. The reversal of 21916239 is 93261912.

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 21916239 - 2³ = 21916231 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21916231) 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, 3652704 + ... + 3652709.

It is an arithmetic number, because the mean of its divisors is an integer number (7305414).

Almost surely, 2^21916239 is an apocalyptic number.

21916239 is a deficient number, since it is larger than the sum of its proper divisors (7305417).

21916239 is an equidigital number, since it uses as much as digits as its factorization.

21916239 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7305416.

The product of its digits is 5832, while the sum is 33.

The square root of 21916239 is about 4681.4782921637. The cubic root of 21916239 is about 279.8478722939.

It can be divided in two parts, 21916 and 239, that added together give a triangular number (22155 = T₂₁₀).

The spelling of 21916239 in words is "twenty-one million, nine hundred sixteen thousand, two hundred thirty-nine".