21211225 has 24 divisors (see below), whose sum is σ = 30567488. Its totient is φ = 14299200.

The previous prime is 21211217. The next prime is 21211237. The reversal of 21211225 is 52211212.

It is a happy number.

It is not a de Polignac number, because 21211225 - 2³ = 21211217 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21211199 and 21211208.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 9682 + ... + 11668.

Almost surely, 2^21211225 is an apocalyptic number.

21211225 is a gapful number since it is divisible by the number (25) formed by its first and last digit.

It is an amenable number.

21211225 is a deficient number, since it is larger than the sum of its proper divisors (9356263).

21211225 is a wasteful number, since it uses less digits than its factorization.

21211225 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2065 (or 2060 counting only the distinct ones).

The product of its digits is 80, while the sum is 16.

The square root of 21211225 is about 4605.5645690838. The cubic root of 21211225 is about 276.8143394804.

Adding to 21211225 its reverse (52211212), we get a palindrome (73422437).

The spelling of 21211225 in words is "twenty-one million, two hundred eleven thousand, two hundred twenty-five".