21125265 has 16 divisors (see below), whose sum is σ = 38629248. Its totient is φ = 9657216.

The previous prime is 21125257. The next prime is 21125267. The reversal of 21125265 is 56252112.

It is a happy number.

It is not a de Polignac number, because 21125265 - 2³ = 21125257 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21125267) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 100492 + ... + 100701.

It is an arithmetic number, because the mean of its divisors is an integer number (2414328).

Almost surely, 2^21125265 is an apocalyptic number.

It is an amenable number.

21125265 is a deficient number, since it is larger than the sum of its proper divisors (17503983).

21125265 is a wasteful number, since it uses less digits than its factorization.

21125265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 201208.

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

The square root of 21125265 is about 4596.2229058217. Note that the first 3 decimals coincide. The cubic root of 21125265 is about 276.4398965965.

Adding to 21125265 its reverse (56252112), we get a palindrome (77377377).

The spelling of 21125265 in words is "twenty-one million, one hundred twenty-five thousand, two hundred sixty-five".