21088825 has 6 divisors (see below), whose sum is σ = 26150174. Its totient is φ = 16871040.

The previous prime is 21088819. The next prime is 21088849. The reversal of 21088825 is 52888012.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 1401856 + 19686969 = 1184^2 + 4437^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21088825 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 (11) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 421752 + ... + 421801.

Almost surely, 2^21088825 is an apocalyptic number.

21088825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21088825 is a deficient number, since it is larger than the sum of its proper divisors (5061349).

21088825 is an equidigital number, since it uses as much as digits as its factorization.

21088825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 843563 (or 843558 counting only the distinct ones).

The product of its (nonzero) digits is 10240, while the sum is 34.

The square root of 21088825 is about 4592.2570703304. The cubic root of 21088825 is about 276.2808568959.

The spelling of 21088825 in words is "twenty-one million, eighty-eight thousand, eight hundred twenty-five".