21015056 has 20 divisors (see below), whose sum is σ = 40811004. Its totient is φ = 10483200.

The previous prime is 21015047. The next prime is 21015061. The reversal of 21015056 is 65051012.

It can be written as a sum of positive squares in 2 ways, for example, as 1795600 + 19219456 = 1340^2 + 4384^2 .

It is a hoax number, since the sum of its digits (20) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7076 + ... + 9596.

Almost surely, 2^21015056 is an apocalyptic number.

It is an amenable number.

21015056 is a deficient number, since it is larger than the sum of its proper divisors (19795948).

21015056 is a wasteful number, since it uses less digits than its factorization.

21015056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3050 (or 3044 counting only the distinct ones).

The product of its (nonzero) digits is 300, while the sum is 20.

The square root of 21015056 is about 4584.2181448967. The cubic root of 21015056 is about 275.9583357958.

Adding to 21015056 its reverse (65051012), we get a palindrome (86066068).

The spelling of 21015056 in words is "twenty-one million, fifteen thousand, fifty-six".