21866895 has 16 divisors (see below), whose sum is σ = 38874720. Its totient is φ = 11662272.

The previous prime is 21866893. The next prime is 21866903. The reversal of 21866895 is 59866812.

It is not a de Polignac number, because 21866895 - 2¹ = 21866893 is a prime.

It is a super-2 number, since 2×21866895² = 956322193882050, which contains 22 as substring.

It is a Smith number, since the sum of its digits (45) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a self number, because there is not a number n which added to its sum of digits gives 21866895.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21866893) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 80854 + ... + 81123.

It is an arithmetic number, because the mean of its divisors is an integer number (2429670).

Almost surely, 2^21866895 is an apocalyptic number.

21866895 is a deficient number, since it is larger than the sum of its proper divisors (17007825).

21866895 is a wasteful number, since it uses less digits than its factorization.

21866895 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161991 (or 161985 counting only the distinct ones).

The product of its digits is 207360, while the sum is 45.

The square root of 21866895 is about 4676.2051922472. The cubic root of 21866895 is about 279.6376904007.

The spelling of 21866895 in words is "twenty-one million, eight hundred sixty-six thousand, eight hundred ninety-five".