21902389 has 4 divisors (see below), whose sum is σ = 21941856. Its totient is φ = 21862924.

The previous prime is 21902347. The next prime is 21902407. The reversal of 21902389 is 98320912.

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 21902389 - 2¹¹ = 21900341 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21902339) 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, 18889 + ... + 20014.

It is an arithmetic number, because the mean of its divisors is an integer number (5485464).

Almost surely, 2^21902389 is an apocalyptic number.

It is an amenable number.

21902389 is a deficient number, since it is larger than the sum of its proper divisors (39467).

21902389 is an equidigital number, since it uses as much as digits as its factorization.

21902389 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39466.

The product of its (nonzero) digits is 7776, while the sum is 34.

The square root of 21902389 is about 4679.9988247862. The cubic root of 21902389 is about 279.7889097780.

The spelling of 21902389 in words is "twenty-one million, nine hundred two thousand, three hundred eighty-nine".