21864873 has 12 divisors (see below), whose sum is σ = 30970160. Its totient is φ = 13718592.

The previous prime is 21864859. The next prime is 21864883. The reversal of 21864873 is 37846812.

It is not a de Polignac number, because 21864873 - 2⁸ = 21864617 is a prime.

It is a super-2 number, since 2×21864873² = 956145342612258, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21864853) 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, 11743 + ... + 13476.

Almost surely, 2^21864873 is an apocalyptic number.

It is an amenable number.

21864873 is a deficient number, since it is larger than the sum of its proper divisors (9105287).

21864873 is a wasteful number, since it uses less digits than its factorization.

21864873 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 25256 (or 25239 counting only the distinct ones).

The product of its digits is 64512, while the sum is 39.

The square root of 21864873 is about 4675.9889863001. The cubic root of 21864873 is about 279.6290709047.

The spelling of 21864873 in words is "twenty-one million, eight hundred sixty-four thousand, eight hundred seventy-three".