21320225 has 6 divisors (see below), whose sum is σ = 26437110. Its totient is φ = 17056160.

The previous prime is 21320213. The next prime is 21320239. The reversal of 21320225 is 52202312.

It can be written as a sum of positive squares in 3 ways, for example, as 12769 + 21307456 = 113^2 + 4616^2 .

It is not a de Polignac number, because 21320225 - 2⁴ = 21320209 is a prime.

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, 426380 + ... + 426429.

It is an arithmetic number, because the mean of its divisors is an integer number (4406185).

Almost surely, 2^21320225 is an apocalyptic number.

21320225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21320225 is a deficient number, since it is larger than the sum of its proper divisors (5116885).

21320225 is an equidigital number, since it uses as much as digits as its factorization.

21320225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 852819 (or 852814 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 21320225 is about 4617.3829167614. The cubic root of 21320225 is about 277.2876930347.

Adding to 21320225 its reverse (52202312), we get a palindrome (73522537).

The spelling of 21320225 in words is "twenty-one million, three hundred twenty thousand, two hundred twenty-five".