21304925 has 6 divisors (see below), whose sum is σ = 26418138. Its totient is φ = 17043920.

The previous prime is 21304919. The next prime is 21304931. The reversal of 21304925 is 52940312.

It is an interprime number because it is at equal distance from previous prime (21304919) and next prime (21304931).

It can be written as a sum of positive squares in 3 ways, for example, as 273529 + 21031396 = 523^2 + 4586^2 .

It is not a de Polignac number, because 21304925 - 2¹⁰ = 21303901 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21304894 and 21304903.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 426074 + ... + 426123.

It is an arithmetic number, because the mean of its divisors is an integer number (4403023).

Almost surely, 2^21304925 is an apocalyptic number.

21304925 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21304925 is a deficient number, since it is larger than the sum of its proper divisors (5113213).

21304925 is an equidigital number, since it uses as much as digits as its factorization.

21304925 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 852207 (or 852202 counting only the distinct ones).

The product of its (nonzero) digits is 2160, while the sum is 26.

The square root of 21304925 is about 4615.7258367455. The cubic root of 21304925 is about 277.2213473159.

The spelling of 21304925 in words is "twenty-one million, three hundred four thousand, nine hundred twenty-five".