21166425 has 72 divisors (see below), whose sum is σ = 44104320. Its totient is φ = 9504000.

The previous prime is 21166381. The next prime is 21166441. The reversal of 21166425 is 52466112.

21166425 is a `hidden beast` number, since 2 + 1 + 16 + 642 + 5 = 666.

It is not a de Polignac number, because 21166425 - 2⁷ = 21166297 is a prime.

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 71 ways as a sum of consecutive naturals, for example, 140100 + ... + 140250.

It is an arithmetic number, because the mean of its divisors is an integer number (612560).

Almost surely, 2^21166425 is an apocalyptic number.

21166425 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21166425 is an abundant number, since it is smaller than the sum of its proper divisors (22937895).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21166425 is a wasteful number, since it uses less digits than its factorization.

21166425 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 263 (or 255 counting only the distinct ones).

The product of its digits is 2880, while the sum is 27.

The square root of 21166425 is about 4600.6983165602. The cubic root of 21166425 is about 276.6193165851.

The spelling of 21166425 in words is "twenty-one million, one hundred sixty-six thousand, four hundred twenty-five".