21225165 has 32 divisors (see below), whose sum is σ = 37013760. Its totient is φ = 10323456.

The previous prime is 21225121. The next prime is 21225179. The reversal of 21225165 is 56152212.

It is a happy number.

It is not a de Polignac number, because 21225165 - 2⁷ = 21225037 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 16744 + ... + 17966.

It is an arithmetic number, because the mean of its divisors is an integer number (1156680).

Almost surely, 2^21225165 is an apocalyptic number.

It is an amenable number.

21225165 is a deficient number, since it is larger than the sum of its proper divisors (15788595).

21225165 is a wasteful number, since it uses less digits than its factorization.

21225165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1333.

The product of its digits is 1200, while the sum is 24.

The square root of 21225165 is about 4607.0777071806. The cubic root of 21225165 is about 276.8749669213.

Adding to 21225165 its reverse (56152212), we get a palindrome (77377377).

The spelling of 21225165 in words is "twenty-one million, two hundred twenty-five thousand, one hundred sixty-five".