21256625 has 32 divisors (see below), whose sum is σ = 29073408. Its totient is φ = 15422400.

The previous prime is 21256597. The next prime is 21256633. The reversal of 21256625 is 52665212.

It is not a de Polignac number, because 21256625 - 2⁸ = 21256369 is a prime.

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 31 ways as a sum of consecutive naturals, for example, 167312 + ... + 167438.

It is an arithmetic number, because the mean of its divisors is an integer number (908544).

Almost surely, 2^21256625 is an apocalyptic number.

21256625 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21256625 is a deficient number, since it is larger than the sum of its proper divisors (7816783).

21256625 is a wasteful number, since it uses less digits than its factorization.

21256625 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 258 (or 248 counting only the distinct ones).

The product of its digits is 7200, while the sum is 29.

The square root of 21256625 is about 4610.4907547896. The cubic root of 21256625 is about 277.0116943457.

The spelling of 21256625 in words is "twenty-one million, two hundred fifty-six thousand, six hundred twenty-five".