21104225 has 36 divisors (see below), whose sum is σ = 29236224. Its totient is φ = 15079680.

The previous prime is 21104221. The next prime is 21104233. The reversal of 21104225 is 52240112.

It is not a de Polignac number, because 21104225 - 2² = 21104221 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21104221) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 166112 + ... + 166238.

Almost surely, 2^21104225 is an apocalyptic number.

21104225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21104225 is a deficient number, since it is larger than the sum of its proper divisors (8131999).

21104225 is a wasteful number, since it uses less digits than its factorization.

21104225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 194 (or 172 counting only the distinct ones).

The product of its (nonzero) digits is 160, while the sum is 17.

The square root of 21104225 is about 4593.9334997364. The cubic root of 21104225 is about 276.3480913981.

Adding to 21104225 its reverse (52240112), we get a palindrome (73344337).

The spelling of 21104225 in words is "twenty-one million, one hundred four thousand, two hundred twenty-five".