21292225 has 6 divisors (see below), whose sum is σ = 26402390. Its totient is φ = 17033760.

The previous prime is 21292189. The next prime is 21292231. The reversal of 21292225 is 52229212.

It can be written as a sum of positive squares in 3 ways, for example, as 4260096 + 17032129 = 2064^2 + 4127^2 .

It is a de Polignac number, because none of the positive numbers 2^k-21292225 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (25), and also a Moran number because the ratio is a prime number: 851689 = 21292225 / (2 + 1 + 2 + 9 + 2 + 2 + 2 + 5).

It is a self number, because there is not a number n which added to its sum of digits gives 21292225.

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, 425820 + ... + 425869.

Almost surely, 2^21292225 is an apocalyptic number.

21292225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21292225 is a deficient number, since it is larger than the sum of its proper divisors (5110165).

21292225 is an equidigital number, since it uses as much as digits as its factorization.

21292225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 851699 (or 851694 counting only the distinct ones).

The product of its digits is 1440, while the sum is 25.

The square root of 21292225 is about 4614.3499000401. The cubic root of 21292225 is about 277.1662519031.

The spelling of 21292225 in words is "twenty-one million, two hundred ninety-two thousand, two hundred twenty-five".