21856899 has 16 divisors (see below), whose sum is σ = 30098432. Its totient is φ = 14097888.

The previous prime is 21856889. The next prime is 21856903. The reversal of 21856899 is 99865812.

It is a happy number.

It is not a de Polignac number, because 21856899 - 2⁵ = 21856867 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21856889) 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, 24312 + ... + 25194.

It is an arithmetic number, because the mean of its divisors is an integer number (1881152).

Almost surely, 2^21856899 is an apocalyptic number.

21856899 is a deficient number, since it is larger than the sum of its proper divisors (8241533).

21856899 is a wasteful number, since it uses less digits than its factorization.

21856899 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1146.

The product of its digits is 311040, while the sum is 48.

The square root of 21856899 is about 4675.1362546989. The cubic root of 21856899 is about 279.5950737055.

The spelling of 21856899 in words is "twenty-one million, eight hundred fifty-six thousand, eight hundred ninety-nine".