21275225 has 6 divisors (see below), whose sum is σ = 26381310. Its totient is φ = 17020160.

The previous prime is 21275209. The next prime is 21275237. The reversal of 21275225 is 52257212.

It can be written as a sum of positive squares in 3 ways, for example, as 87616 + 21187609 = 296^2 + 4603^2 .

It is not a de Polignac number, because 21275225 - 2⁴ = 21275209 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21275194 and 21275203.

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, 425480 + ... + 425529.

It is an arithmetic number, because the mean of its divisors is an integer number (4396885).

Almost surely, 2^21275225 is an apocalyptic number.

21275225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21275225 is a deficient number, since it is larger than the sum of its proper divisors (5106085).

21275225 is an equidigital number, since it uses as much as digits as its factorization.

21275225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 851019 (or 851014 counting only the distinct ones).

The product of its digits is 2800, while the sum is 26.

The square root of 21275225 is about 4612.5074525685. The cubic root of 21275225 is about 277.0924678366.

The spelling of 21275225 in words is "twenty-one million, two hundred seventy-five thousand, two hundred twenty-five".