21545044 has 12 divisors (see below), whose sum is σ = 37867284. Its totient is φ = 10725824.

The previous prime is 21545039. The next prime is 21545047. The reversal of 21545044 is 44054512.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 1295044 + 20250000 = 1138^2 + 4500^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21545047) 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, 10627 + ... + 12490.

It is an arithmetic number, because the mean of its divisors is an integer number (3155607).

Almost surely, 2^21545044 is an apocalyptic number.

It is an amenable number.

21545044 is a deficient number, since it is larger than the sum of its proper divisors (16322240).

21545044 is a wasteful number, since it uses less digits than its factorization.

21545044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23354 (or 23352 counting only the distinct ones).

The product of its (nonzero) digits is 3200, while the sum is 25.

The square root of 21545044 is about 4641.6639257921. The cubic root of 21545044 is about 278.2589413179.

Adding to 21545044 its reverse (44054512), we get a palindrome (65599556).

The spelling of 21545044 in words is "twenty-one million, five hundred forty-five thousand, forty-four".