21051875 has 20 divisors (see below), whose sum is σ = 28340928. Its totient is φ = 15540000.

The previous prime is 21051859. The next prime is 21051887. The reversal of 21051875 is 57815012.

It is not a de Polignac number, because 21051875 - 2⁴ = 21051859 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 6830 + ... + 9420.

Almost surely, 2^21051875 is an apocalyptic number.

21051875 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21051875 is a deficient number, since it is larger than the sum of its proper divisors (7289053).

21051875 is an equidigital number, since it uses as much as digits as its factorization.

21051875 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2624 (or 2609 counting only the distinct ones).

The product of its (nonzero) digits is 2800, while the sum is 29.

The square root of 21051875 is about 4588.2322303911. The cubic root of 21051875 is about 276.1194041571.

Adding to 21051875 its reverse (57815012), we get a palindrome (78866887).

The spelling of 21051875 in words is "twenty-one million, fifty-one thousand, eight hundred seventy-five".