21618875 has 16 divisors (see below), whose sum is σ = 27273792. Its totient is φ = 17107200.

The previous prime is 21618847. The next prime is 21618889. The reversal of 21618875 is 57881612.

It is not a de Polignac number, because 21618875 - 2¹⁴ = 21602491 is a prime.

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 15 ways as a sum of consecutive naturals, for example, 11234 + ... + 13016.

It is an arithmetic number, because the mean of its divisors is an integer number (1704612).

Almost surely, 2^21618875 is an apocalyptic number.

21618875 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21618875 is a deficient number, since it is larger than the sum of its proper divisors (5654917).

21618875 is an equidigital number, since it uses as much as digits as its factorization.

21618875 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1895 (or 1885 counting only the distinct ones).

The product of its digits is 26880, while the sum is 38.

The square root of 21618875 is about 4649.6101987156. The cubic root of 21618875 is about 278.5764267598.

It can be divided in two parts, 216 and 18875, that added together give a palindrome (19091).

The spelling of 21618875 in words is "twenty-one million, six hundred eighteen thousand, eight hundred seventy-five".