21131225 has 12 divisors (see below), whose sum is σ = 26307840. Its totient is φ = 16837200.

The previous prime is 21131191. The next prime is 21131251. The reversal of 21131225 is 52213112.

It is a happy number.

It is not a de Polignac number, because 21131225 - 2⁶ = 21131161 is a prime.

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, 5216 + ... + 8334.

It is an arithmetic number, because the mean of its divisors is an integer number (2192320).

Almost surely, 2^21131225 is an apocalyptic number.

21131225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21131225 is a deficient number, since it is larger than the sum of its proper divisors (5176615).

21131225 is a wasteful number, since it uses less digits than its factorization.

21131225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3400 (or 3395 counting only the distinct ones).

The product of its digits is 120, while the sum is 17.

The square root of 21131225 is about 4596.8712185572. The cubic root of 21131225 is about 276.4658911717.

Adding to 21131225 its reverse (52213112), we get a palindrome (73344337).

The spelling of 21131225 in words is "twenty-one million, one hundred thirty-one thousand, two hundred twenty-five".