21828645 has 12 divisors (see below), whose sum is σ = 37836396. Its totient is φ = 11641920.

The previous prime is 21828623. The next prime is 21828659. The reversal of 21828645 is 54682812.

21828645 is a `hidden beast` number, since 2 + 1 + 8 + 2 + 8 + 645 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 7403841 + 14424804 = 2721^2 + 3798^2 .

It is not a de Polignac number, because 21828645 - 2⁵ = 21828613 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 242496 + ... + 242585.

It is an arithmetic number, because the mean of its divisors is an integer number (3153033).

Almost surely, 2^21828645 is an apocalyptic number.

It is an amenable number.

21828645 is a deficient number, since it is larger than the sum of its proper divisors (16007751).

21828645 is a wasteful number, since it uses less digits than its factorization.

21828645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 485092 (or 485089 counting only the distinct ones).

The product of its digits is 30720, while the sum is 36.

The square root of 21828645 is about 4672.1135474216. The cubic root of 21828645 is about 279.4745460012.

The spelling of 21828645 in words is "twenty-one million, eight hundred twenty-eight thousand, six hundred forty-five".