21286825 has 18 divisors (see below), whose sum is σ = 30706926. Its totient is φ = 14595840.

The previous prime is 21286823. The next prime is 21286871. The reversal of 21286825 is 52868212.

It can be written as a sum of positive squares in 3 ways, for example, as 7056 + 21279769 = 84^2 + 4613^2 .

It is not a de Polignac number, because 21286825 - 2¹ = 21286823 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21286823) by changing a digit.

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 17 ways as a sum of consecutive naturals, for example, 7464 + ... + 9913.

Almost surely, 2^21286825 is an apocalyptic number.

21286825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21286825 is a deficient number, since it is larger than the sum of its proper divisors (9420101).

21286825 is a wasteful number, since it uses less digits than its factorization.

21286825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17401 (or 17389 counting only the distinct ones).

The product of its digits is 15360, while the sum is 34.

The square root of 21286825 is about 4613.7647317565. The cubic root of 21286825 is about 277.1428188690.

The spelling of 21286825 in words is "twenty-one million, two hundred eighty-six thousand, eight hundred twenty-five".