21045736 has 24 divisors (see below), whose sum is σ = 41259330. Its totient is φ = 10063328.

The previous prime is 21045727. The next prime is 21045737. The reversal of 21045736 is 63754012.

It can be written as a sum of positive squares in only one way, i.e., 16760836 + 4284900 = 4094^2 + 2070^2 .

It is not an unprimeable number, because it can be changed into a prime (21045737) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1746 + ... + 6718.

Almost surely, 2^21045736 is an apocalyptic number.

It is an amenable number.

21045736 is a deficient number, since it is larger than the sum of its proper divisors (20213594).

21045736 is a wasteful number, since it uses less digits than its factorization.

21045736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5025 (or 4998 counting only the distinct ones).

The product of its (nonzero) digits is 5040, while the sum is 28.

The square root of 21045736 is about 4587.5631875757. The cubic root of 21045736 is about 276.0925615469.

Adding to 21045736 its reverse (63754012), we get a palindrome (84799748).

The spelling of 21045736 in words is "twenty-one million, forty-five thousand, seven hundred thirty-six".