21072225 has 12 divisors (see below), whose sum is σ = 34839536. Its totient is φ = 11238480.

The previous prime is 21072211. The next prime is 21072229. The reversal of 21072225 is 52227012.

It is a happy number.

It is not a de Polignac number, because 21072225 - 2²⁰ = 20023649 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21072229) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 140407 + ... + 140556.

Almost surely, 2^21072225 is an apocalyptic number.

21072225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21072225 is a deficient number, since it is larger than the sum of its proper divisors (13767311).

21072225 is a wasteful number, since it uses less digits than its factorization.

21072225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 280976 (or 280971 counting only the distinct ones).

The product of its (nonzero) digits is 560, while the sum is 21.

The square root of 21072225 is about 4590.4493244126. The cubic root of 21072225 is about 276.2083466746.

Adding to 21072225 its reverse (52227012), we get a palindrome (73299237).

The spelling of 21072225 in words is "twenty-one million, seventy-two thousand, two hundred twenty-five".