21168925 has 6 divisors (see below), whose sum is σ = 26249498. Its totient is φ = 16935120.

The previous prime is 21168923. The next prime is 21168949. The reversal of 21168925 is 52986112.

It can be written as a sum of positive squares in 3 ways, for example, as 4301476 + 16867449 = 2074^2 + 4107^2 .

It is not a de Polignac number, because 21168925 - 2¹ = 21168923 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21168923) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 423354 + ... + 423403.

Almost surely, 2^21168925 is an apocalyptic number.

21168925 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21168925 is a deficient number, since it is larger than the sum of its proper divisors (5080573).

21168925 is an equidigital number, since it uses as much as digits as its factorization.

21168925 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 846767 (or 846762 counting only the distinct ones).

The product of its digits is 8640, while the sum is 34.

The square root of 21168925 is about 4600.9700064226. The cubic root of 21168925 is about 276.6302068049.

The spelling of 21168925 in words is "twenty-one million, one hundred sixty-eight thousand, nine hundred twenty-five".