21888251 has 12 divisors (see below), whose sum is σ = 27777240. Its totient is φ = 17055360.

The previous prime is 21888199. The next prime is 21888259. The reversal of 21888251 is 15288812.

It is not a de Polignac number, because 21888251 - 2²² = 17693947 is a prime.

It is a Smith number, since the sum of its digits (35) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21888259) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19766 + ... + 20843.

It is an arithmetic number, because the mean of its divisors is an integer number (2314770).

Almost surely, 2^21888251 is an apocalyptic number.

21888251 is a deficient number, since it is larger than the sum of its proper divisors (5888989).

21888251 is a wasteful number, since it uses less digits than its factorization.

21888251 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40634 (or 40627 counting only the distinct ones).

The product of its digits is 10240, while the sum is 35.

The square root of 21888251 is about 4678.4881104904. The cubic root of 21888251 is about 279.7286955393.

The spelling of 21888251 in words is "twenty-one million, eight hundred eighty-eight thousand, two hundred fifty-one".