21056516 has 24 divisors (see below), whose sum is σ = 39842880. Its totient is φ = 9679392.

The previous prime is 21056507. The next prime is 21056527. The reversal of 21056516 is 61565012.

It is a Harshad number since it is a multiple of its sum of digits (26).

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 7 ways as a sum of consecutive naturals, for example, 15305 + ... + 16623.

It is an arithmetic number, because the mean of its divisors is an integer number (1660120).

Almost surely, 2^21056516 is an apocalyptic number.

21056516 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21056516 is a deficient number, since it is larger than the sum of its proper divisors (18786364).

21056516 is a wasteful number, since it uses less digits than its factorization.

21056516 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1643 (or 1641 counting only the distinct ones).

The product of its (nonzero) digits is 1800, while the sum is 26.

The square root of 21056516 is about 4588.7379528581. The cubic root of 21056516 is about 276.1396933395.

The spelling of 21056516 in words is "twenty-one million, fifty-six thousand, five hundred sixteen".