21888889 has 4 divisors (see below), whose sum is σ = 23878800. Its totient is φ = 19898980.

The previous prime is 21888871. The next prime is 21888899. The reversal of 21888889 is 98888812.

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 21888889 - 2¹³ = 21880697 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21888859) 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, 994939 + ... + 994960.

It is an arithmetic number, because the mean of its divisors is an integer number (5969700).

Almost surely, 2^21888889 is an apocalyptic number.

It is an amenable number.

21888889 is a deficient number, since it is larger than the sum of its proper divisors (1989911).

21888889 is a wasteful number, since it uses less digits than its factorization.

21888889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1989910.

The product of its digits is 589824, while the sum is 52.

The square root of 21888889 is about 4678.5562944139. The cubic root of 21888889 is about 279.7314133622.

The spelling of 21888889 in words is "twenty-one million, eight hundred eighty-eight thousand, eight hundred eighty-nine".