21768925 has 36 divisors (see below), whose sum is σ = 30149856. Its totient is φ = 15558400.

The previous prime is 21768917. The next prime is 21768931. The reversal of 21768925 is 52986712.

It is not a de Polignac number, because 21768925 - 2³ = 21768917 is a prime.

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 (13) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 166110 + ... + 166240.

It is an arithmetic number, because the mean of its divisors is an integer number (837496).

Almost surely, 2^21768925 is an apocalyptic number.

21768925 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21768925 is a deficient number, since it is larger than the sum of its proper divisors (8380931).

21768925 is a wasteful number, since it uses less digits than its factorization.

21768925 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 198 (or 176 counting only the distinct ones).

The product of its digits is 60480, while the sum is 40.

The square root of 21768925 is about 4665.7180583486. The cubic root of 21768925 is about 279.2194459750.

The spelling of 21768925 in words is "twenty-one million, seven hundred sixty-eight thousand, nine hundred twenty-five".