21285775 has 12 divisors (see below), whose sum is σ = 30165232. Its totient is φ = 14595840.

The previous prime is 21285769. The next prime is 21285791. The reversal of 21285775 is 57758212.

It is not a de Polignac number, because 21285775 - 2⁷ = 21285647 is a prime.

It is a Duffinian number.

It is a congruent 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 11 ways as a sum of consecutive naturals, for example, 60642 + ... + 60991.

Almost surely, 2^21285775 is an apocalyptic number.

21285775 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

21285775 is a deficient number, since it is larger than the sum of its proper divisors (8879457).

21285775 is a wasteful number, since it uses less digits than its factorization.

21285775 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 121650 (or 121645 counting only the distinct ones).

The product of its digits is 39200, while the sum is 37.

The square root of 21285775 is about 4613.6509404158. The cubic root of 21285775 is about 277.1382619855.

The spelling of 21285775 in words is "twenty-one million, two hundred eighty-five thousand, seven hundred seventy-five".