21057084 has 60 divisors (see below), whose sum is σ = 58300704. Its totient is φ = 6604416.

The previous prime is 21057083. The next prime is 21057131. The reversal of 21057084 is 48075012.

21057084 is a `hidden beast` number, since 2 + 10 + 570 + 84 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21057083) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 3597 + ... + 7419.

Almost surely, 2^21057084 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 21057084, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29150352).

21057084 is an abundant number, since it is smaller than the sum of its proper divisors (37243620).

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

21057084 is a wasteful number, since it uses less digits than its factorization.

21057084 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3856 (or 3845 counting only the distinct ones).

The product of its (nonzero) digits is 2240, while the sum is 27.

The square root of 21057084 is about 4588.7998430962. The cubic root of 21057084 is about 276.1421762754.

The spelling of 21057084 in words is "twenty-one million, fifty-seven thousand, eighty-four".