21544887 has 16 divisors (see below), whose sum is σ = 35356160. Its totient is φ = 11364192.

The previous prime is 21544877. The next prime is 21544889. The reversal of 21544887 is 78844512.

It is a happy number.

It is not a de Polignac number, because 21544887 - 2⁶ = 21544823 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

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, 39187 + ... + 39732.

It is an arithmetic number, because the mean of its divisors is an integer number (2209760).

Almost surely, 2^21544887 is an apocalyptic number.

21544887 is a deficient number, since it is larger than the sum of its proper divisors (13811273).

21544887 is a wasteful number, since it uses less digits than its factorization.

21544887 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78942.

The product of its digits is 71680, while the sum is 39.

The square root of 21544887 is about 4641.6470137226. The cubic root of 21544887 is about 278.2582654198.

The spelling of 21544887 in words is "twenty-one million, five hundred forty-four thousand, eight hundred eighty-seven".