21008925 has 36 divisors (see below), whose sum is σ = 43008160. Its totient is φ = 9603360.

The previous prime is 21008903. The next prime is 21008941. The reversal of 21008925 is 52980012.

It is not a de Polignac number, because 21008925 - 2⁵ = 21008893 is a prime.

It is a zygodrome in base 13.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 5095 + ... + 8244.

Almost surely, 2^21008925 is an apocalyptic number.

21008925 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21008925 is an abundant number, since it is smaller than the sum of its proper divisors (21999235).

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

21008925 is a wasteful number, since it uses less digits than its factorization.

21008925 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13362 (or 13354 counting only the distinct ones).

The product of its (nonzero) digits is 1440, while the sum is 27.

The square root of 21008925 is about 4583.5493888470. The cubic root of 21008925 is about 275.9314968616.

Adding to 21008925 its reverse (52980012), we get a palindrome (73988937).

It can be divided in two parts, 2100 and 8925, that added together give a square (11025 = 105²).

The spelling of 21008925 in words is "twenty-one million, eight thousand, nine hundred twenty-five".