21684325 has 12 divisors (see below), whose sum is σ = 28957348. Its totient is φ = 16012800.

The previous prime is 21684319. The next prime is 21684347. The reversal of 21684325 is 52348612.

It can be written as a sum of positive squares in 6 ways, for example, as 2735716 + 18948609 = 1654^2 + 4353^2 .

It is not a de Polignac number, because 21684325 - 2³ = 21684317 is a prime.

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

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 (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 33036 + ... + 33685.

Almost surely, 2^21684325 is an apocalyptic number.

21684325 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21684325 is a deficient number, since it is larger than the sum of its proper divisors (7273023).

21684325 is a wasteful number, since it uses less digits than its factorization.

21684325 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 66744 (or 66739 counting only the distinct ones).

The product of its digits is 11520, while the sum is 31.

The square root of 21684325 is about 4656.6431042114. The cubic root of 21684325 is about 278.8572686688.

The spelling of 21684325 in words is "twenty-one million, six hundred eighty-four thousand, three hundred twenty-five".