21002875 has 8 divisors (see below), whose sum is σ = 26211744. Its totient is φ = 16802200.

The previous prime is 21002857. The next prime is 21002881. The reversal of 21002875 is 57820012.

It is not a de Polignac number, because 21002875 - 2⁷ = 21002747 is a prime.

It is a super-2 number, since 2×21002875² = 882241516531250, which contains 22 as substring.

It is a hoax number, since the sum of its digits (25) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (25).

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 83887 + ... + 84136.

It is an arithmetic number, because the mean of its divisors is an integer number (3276468).

Almost surely, 2^21002875 is an apocalyptic number.

21002875 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21002875 is a deficient number, since it is larger than the sum of its proper divisors (5208869).

21002875 is an equidigital number, since it uses as much as digits as its factorization.

21002875 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 168038 (or 168028 counting only the distinct ones).

The product of its (nonzero) digits is 1120, while the sum is 25.

The square root of 21002875 is about 4582.8893724374. The cubic root of 21002875 is about 275.9050073922.

Adding to 21002875 its reverse (57820012), we get a palindrome (78822887).

The spelling of 21002875 in words is "twenty-one million, two thousand, eight hundred seventy-five".