21544899 has 16 divisors (see below), whose sum is σ = 30523392. Its totient is φ = 13470848.

The previous prime is 21544889. The next prime is 21544903. The reversal of 21544899 is 99844512.

It is a cyclic number.

It is not a de Polignac number, because 21544899 - 2⁵ = 21544867 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21544899.

It is not an unprimeable number, because it can be changed into a prime (21544889) 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, 18982 + ... + 20084.

It is an arithmetic number, because the mean of its divisors is an integer number (1907712).

Almost surely, 2^21544899 is an apocalyptic number.

21544899 is a deficient number, since it is larger than the sum of its proper divisors (8978493).

21544899 is a wasteful number, since it uses less digits than its factorization.

21544899 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1506.

The product of its digits is 103680, while the sum is 42.

The square root of 21544899 is about 4641.6483063670. The cubic root of 21544899 is about 278.2583170809.

The spelling of 21544899 in words is "twenty-one million, five hundred forty-four thousand, eight hundred ninety-nine".