21393825 has 12 divisors (see below), whose sum is σ = 35371248. Its totient is φ = 11410000.

The previous prime is 21393809. The next prime is 21393847. The reversal of 21393825 is 52839312.

It is not a de Polignac number, because 21393825 - 2⁴ = 21393809 is a prime.

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, 142551 + ... + 142700.

It is an arithmetic number, because the mean of its divisors is an integer number (2947604).

Almost surely, 2^21393825 is an apocalyptic number.

21393825 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21393825 is a deficient number, since it is larger than the sum of its proper divisors (13977423).

21393825 is a wasteful number, since it uses less digits than its factorization.

21393825 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 285264 (or 285259 counting only the distinct ones).

The product of its digits is 12960, while the sum is 33.

The square root of 21393825 is about 4625.3459330087. The cubic root of 21393825 is about 277.6064034780.

The spelling of 21393825 in words is "twenty-one million, three hundred ninety-three thousand, eight hundred twenty-five".