21100225 has 12 divisors (see below), whose sum is σ = 26248320. Its totient is φ = 16826000.

The previous prime is 21100217. The next prime is 21100231. The reversal of 21100225 is 52200112.

It is not a de Polignac number, because 21100225 - 2³ = 21100217 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 7800 + ... + 10150.

It is an arithmetic number, because the mean of its divisors is an integer number (2187360).

Almost surely, 2^21100225 is an apocalyptic number.

21100225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21100225 is a deficient number, since it is larger than the sum of its proper divisors (5148095).

21100225 is a wasteful number, since it uses less digits than its factorization.

21100225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2720 (or 2715 counting only the distinct ones).

The product of its (nonzero) digits is 40, while the sum is 13.

The square root of 21100225 is about 4593.4981223464. The cubic root of 21100225 is about 276.3306310364.

Adding to 21100225 its reverse (52200112), we get a palindrome (73300337).

The spelling of 21100225 in words is "twenty-one million, one hundred thousand, two hundred twenty-five".