21888138 has 16 divisors (see below), whose sum is σ = 43832160. Its totient is φ = 7286736.

The previous prime is 21888131. The next prime is 21888151. The reversal of 21888138 is 83188812.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21888096 and 21888105.

It is not an unprimeable number, because it can be changed into a prime (21888131) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4153 + ... + 7811.

It is an arithmetic number, because the mean of its divisors is an integer number (2739510).

Almost surely, 2^21888138 is an apocalyptic number.

21888138 is an abundant number, since it is smaller than the sum of its proper divisors (21944022).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21888138 is a wasteful number, since it uses less digits than its factorization.

21888138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4661.

The product of its digits is 24576, while the sum is 39.

The square root of 21888138 is about 4678.4760339239. The cubic root of 21888138 is about 279.7282141639.

The spelling of 21888138 in words is "twenty-one million, eight hundred eighty-eight thousand, one hundred thirty-eight".