21045244 has 24 divisors (see below), whose sum is σ = 40841136. Its totient is φ = 9408000.

The previous prime is 21045239. The next prime is 21045257. The reversal of 21045244 is 44254012.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 1237 + ... + 6604.

It is an arithmetic number, because the mean of its divisors is an integer number (1701714).

Almost surely, 2^21045244 is an apocalyptic number.

It is an amenable number.

21045244 is a deficient number, since it is larger than the sum of its proper divisors (19795892).

21045244 is a wasteful number, since it uses less digits than its factorization.

21045244 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7917 (or 7915 counting only the distinct ones).

The product of its (nonzero) digits is 1280, while the sum is 22.

The square root of 21045244 is about 4587.5095640227. The cubic root of 21045244 is about 276.0904100644.

Adding to 21045244 its reverse (44254012), we get a palindrome (65299256).

It can be divided in two parts, 210 and 45244, that added together give a palindrome (45454).

The spelling of 21045244 in words is "twenty-one million, forty-five thousand, two hundred forty-four".