21101265 has 24 divisors (see below), whose sum is σ = 37470888. Its totient is φ = 10978560.

The previous prime is 21101263. The next prime is 21101273. The reversal of 21101265 is 56210112.

It can be written as a sum of positive squares in 4 ways, for example, as 88209 + 21013056 = 297^2 + 4584^2 .

It is not a de Polignac number, because 21101265 - 2¹ = 21101263 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21101263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 3874 + ... + 7563.

It is an arithmetic number, because the mean of its divisors is an integer number (1561287).

Almost surely, 2^21101265 is an apocalyptic number.

It is an amenable number.

21101265 is a deficient number, since it is larger than the sum of its proper divisors (16369623).

21101265 is a wasteful number, since it uses less digits than its factorization.

21101265 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11489 (or 11486 counting only the distinct ones).

The product of its (nonzero) digits is 120, while the sum is 18.

The square root of 21101265 is about 4593.6113244375. The cubic root of 21101265 is about 276.3351709427.

Adding to 21101265 its reverse (56210112), we get a palindrome (77311377).

It can be divided in two parts, 2110 and 1265, that added together give a cube (3375 = 15³).

The spelling of 21101265 in words is "twenty-one million, one hundred one thousand, two hundred sixty-five".