21224225 has 24 divisors (see below), whose sum is σ = 29007072. Its totient is φ = 15276800.

The previous prime is 21224207. The next prime is 21224249. The reversal of 21224225 is 52242212.

It is not a de Polignac number, because 21224225 - 2¹⁴ = 21207841 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21224197 and 21224206.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 30734 + ... + 31416.

It is an arithmetic number, because the mean of its divisors is an integer number (1208628).

Almost surely, 2^21224225 is an apocalyptic number.

21224225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21224225 is a deficient number, since it is larger than the sum of its proper divisors (7782847).

21224225 is a wasteful number, since it uses less digits than its factorization.

21224225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 817 (or 812 counting only the distinct ones).

The product of its digits is 640, while the sum is 20.

The square root of 21224225 is about 4606.9756891045. The cubic root of 21224225 is about 276.8708795355.

Adding to 21224225 its reverse (52242212), we get a palindrome (73466437).

The spelling of 21224225 in words is "twenty-one million, two hundred twenty-four thousand, two hundred twenty-five".