21857364 has 72 divisors (see below), whose sum is σ = 58094400. Its totient is φ = 7185024.

The previous prime is 21857357. The next prime is 21857377. The reversal of 21857364 is 46375812.

21857364 is a `hidden beast` number, since 21 + 8 + 573 + 64 = 666.

It is a super-3 number, since 3×21857364³ (a number of 23 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 109737 + ... + 109935.

Almost surely, 2^21857364 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21857364, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29047200).

21857364 is an abundant number, since it is smaller than the sum of its proper divisors (36237036).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21857364 is a wasteful number, since it uses less digits than its factorization.

21857364 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 331 (or 317 counting only the distinct ones).

The product of its digits is 40320, while the sum is 36.

The square root of 21857364 is about 4675.1859856053. The cubic root of 21857364 is about 279.5970564630.

The spelling of 21857364 in words is "twenty-one million, eight hundred fifty-seven thousand, three hundred sixty-four".