21057516 has 24 divisors (see below), whose sum is σ = 54593840. Its totient is φ = 7019136.

The previous prime is 21057511. The next prime is 21057521. The reversal of 21057516 is 61575012.

It is an interprime number because it is at equal distance from previous prime (21057511) and next prime (21057521).

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

It is a self number, because there is not a number n which added to its sum of digits gives 21057516.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21057511) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 97381 + ... + 97596.

Almost surely, 2^21057516 is an apocalyptic number.

It is an amenable number.

21057516 is an abundant number, since it is smaller than the sum of its proper divisors (33536324).

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

21057516 is a wasteful number, since it uses less digits than its factorization.

21057516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 194990 (or 194982 counting only the distinct ones).

The product of its (nonzero) digits is 2100, while the sum is 27.

The square root of 21057516 is about 4588.8469139861. The cubic root of 21057516 is about 276.1440646756.

The spelling of 21057516 in words is "twenty-one million, fifty-seven thousand, five hundred sixteen".