21881233 has 4 divisors (see below), whose sum is σ = 23870448. Its totient is φ = 19892020.

The previous prime is 21881221. The next prime is 21881243. The reversal of 21881233 is 33218812.

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 21881233 - 2⁵ = 21881201 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21881203) 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, 994591 + ... + 994612.

It is an arithmetic number, because the mean of its divisors is an integer number (5967612).

Almost surely, 2^21881233 is an apocalyptic number.

It is an amenable number.

21881233 is a deficient number, since it is larger than the sum of its proper divisors (1989215).

21881233 is a wasteful number, since it uses less digits than its factorization.

21881233 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1989214.

The product of its digits is 2304, while the sum is 28.

The square root of 21881233 is about 4677.7380217366. The cubic root of 21881233 is about 279.6987960004.

The spelling of 21881233 in words is "twenty-one million, eight hundred eighty-one thousand, two hundred thirty-three".