21144415 has 4 divisors (see below), whose sum is σ = 25373304. Its totient is φ = 16915528.

The previous prime is 21144373. The next prime is 21144419. The reversal of 21144415 is 51444112.

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

It is a cyclic number.

It is not a de Polignac number, because 21144415 - 2⁷ = 21144287 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21144419) 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 3 ways as a sum of consecutive naturals, for example, 2114437 + ... + 2114446.

It is an arithmetic number, because the mean of its divisors is an integer number (6343326).

Almost surely, 2^21144415 is an apocalyptic number.

21144415 is a deficient number, since it is larger than the sum of its proper divisors (4228889).

21144415 is an equidigital number, since it uses as much as digits as its factorization.

21144415 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4228888.

The product of its digits is 640, while the sum is 22.

The square root of 21144415 is about 4598.3056662210. The cubic root of 21144415 is about 276.5234020612.

Adding to 21144415 its reverse (51444112), we get a palindrome (72588527).

The spelling of 21144415 in words is "twenty-one million, one hundred forty-four thousand, four hundred fifteen".