21307875 has 16 divisors (see below), whose sum is σ = 35456928. Its totient is φ = 11364000.

The previous prime is 21307859. The next prime is 21307877. The reversal of 21307875 is 57870312.

It is not a de Polignac number, because 21307875 - 2⁴ = 21307859 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21307877) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 28036 + ... + 28785.

It is an arithmetic number, because the mean of its divisors is an integer number (2216058).

Almost surely, 2^21307875 is an apocalyptic number.

21307875 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21307875 is a deficient number, since it is larger than the sum of its proper divisors (14149053).

21307875 is an equidigital number, since it uses as much as digits as its factorization.

21307875 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56839 (or 56829 counting only the distinct ones).

The product of its (nonzero) digits is 11760, while the sum is 33.

The square root of 21307875 is about 4616.0453853921. The cubic root of 21307875 is about 277.2341419355.

The spelling of 21307875 in words is "twenty-one million, three hundred seven thousand, eight hundred seventy-five".