21080225 has 6 divisors (see below), whose sum is σ = 26139510. Its totient is φ = 16864160.

The previous prime is 21080219. The next prime is 21080231. The reversal of 21080225 is 52208012.

It is an interprime number because it is at equal distance from previous prime (21080219) and next prime (21080231).

It can be written as a sum of positive squares in 3 ways, for example, as 1437601 + 19642624 = 1199^2 + 4432^2 .

It is not a de Polignac number, because 21080225 - 2⁶ = 21080161 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21080197 and 21080206.

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, 421580 + ... + 421629.

It is an arithmetic number, because the mean of its divisors is an integer number (4356585).

Almost surely, 2^21080225 is an apocalyptic number.

21080225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21080225 is a deficient number, since it is larger than the sum of its proper divisors (5059285).

21080225 is an equidigital number, since it uses as much as digits as its factorization.

21080225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 843219 (or 843214 counting only the distinct ones).

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 21080225 is about 4591.3206161191. The cubic root of 21080225 is about 276.2432961116.

Adding to 21080225 its reverse (52208012), we get a palindrome (73288237).

The spelling of 21080225 in words is "twenty-one million, eighty thousand, two hundred twenty-five".