21307325 has 24 divisors (see below), whose sum is σ = 29013768. Its totient is φ = 15425280.

The previous prime is 21307283. The next prime is 21307333. The reversal of 21307325 is 52370312.

It can be written as a sum of positive squares in 12 ways, for example, as 4571044 + 16736281 = 2138^2 + 4091^2 .

It is not a de Polignac number, because 21307325 - 2¹⁰ = 21306301 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21307325.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 16607 + ... + 17843.

It is an arithmetic number, because the mean of its divisors is an integer number (1208907).

Almost surely, 2^21307325 is an apocalyptic number.

21307325 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21307325 is a deficient number, since it is larger than the sum of its proper divisors (7706443).

21307325 is a wasteful number, since it uses less digits than its factorization.

21307325 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1313 (or 1308 counting only the distinct ones).

The product of its (nonzero) digits is 1260, while the sum is 23.

The square root of 21307325 is about 4615.9858102035. The cubic root of 21307325 is about 277.2317565875.

Adding to 21307325 its reverse (52370312), we get a palindrome (73677637).

The spelling of 21307325 in words is "twenty-one million, three hundred seven thousand, three hundred twenty-five".