21144265 has 4 divisors (see below), whose sum is σ = 25373124. Its totient is φ = 16915408.

The previous prime is 21144259. The next prime is 21144269. The reversal of 21144265 is 56244112.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 9834496 + 11309769 = 3136^2 + 3363^2 .

It is a cyclic number.

It is not a de Polignac number, because 21144265 - 2²³ = 12755657 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21144269) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2114422 + ... + 2114431.

It is an arithmetic number, because the mean of its divisors is an integer number (6343281).

Almost surely, 2^21144265 is an apocalyptic number.

It is an amenable number.

21144265 is a deficient number, since it is larger than the sum of its proper divisors (4228859).

21144265 is an equidigital number, since it uses as much as digits as its factorization.

21144265 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4228858.

The product of its digits is 1920, while the sum is 25.

The square root of 21144265 is about 4598.2893558366. The cubic root of 21144265 is about 276.5227481674.

Adding to 21144265 its reverse (56244112), we get a palindrome (77388377).

The spelling of 21144265 in words is "twenty-one million, one hundred forty-four thousand, two hundred sixty-five".