21050816 has 14 divisors (see below), whose sum is σ = 41772840. Its totient is φ = 10525376.

The previous prime is 21050807. The next prime is 21050833. The reversal of 21050816 is 61805012.

It is a junction number, because it is equal to n+sod(n) for n = 21050791 and 21050800.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 164396 + ... + 164523.

Almost surely, 2^21050816 is an apocalyptic number.

It is an amenable number.

21050816 is a deficient number, since it is larger than the sum of its proper divisors (20722024).

21050816 is an equidigital number, since it uses as much as digits as its factorization.

21050816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 328931 (or 328921 counting only the distinct ones).

The product of its (nonzero) digits is 480, while the sum is 23.

The square root of 21050816 is about 4588.1168250166. The cubic root of 21050816 is about 276.1147740809.

Adding to 21050816 its reverse (61805012), we get a palindrome (82855828).

The spelling of 21050816 in words is "twenty-one million, fifty thousand, eight hundred sixteen".