21331225 has 12 divisors (see below), whose sum is σ = 27067216. Its totient is φ = 16667280.

The previous prime is 21331217. The next prime is 21331267. The reversal of 21331225 is 52213312.

It is not a de Polignac number, because 21331225 - 2³ = 21331217 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8847 + ... + 10996.

Almost surely, 2^21331225 is an apocalyptic number.

21331225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21331225 is a deficient number, since it is larger than the sum of its proper divisors (5735991).

21331225 is a wasteful number, since it uses less digits than its factorization.

21331225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19896 (or 19891 counting only the distinct ones).

The product of its digits is 360, while the sum is 19.

The square root of 21331225 is about 4618.5739140995. The cubic root of 21331225 is about 277.3353729600.

Adding to 21331225 its reverse (52213312), we get a palindrome (73544537).

The spelling of 21331225 in words is "twenty-one million, three hundred thirty-one thousand, two hundred twenty-five".