21745544 has 8 divisors (see below), whose sum is σ = 40772910. Its totient is φ = 10872768.

The previous prime is 21745543. The next prime is 21745547. The reversal of 21745544 is 44554712.

It can be written as a sum of positive squares in only one way, i.e., 17123044 + 4622500 = 4138^2 + 2150^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a self number, because there is not a number n which added to its sum of digits gives 21745544.

It is not an unprimeable number, because it can be changed into a prime (21745543) 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 as a sum of consecutive naturals, namely, 1359089 + ... + 1359104.

Almost surely, 2^21745544 is an apocalyptic number.

It is an amenable number.

21745544 is a deficient number, since it is larger than the sum of its proper divisors (19027366).

21745544 is a wasteful number, since it uses less digits than its factorization.

21745544 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2718199 (or 2718195 counting only the distinct ones).

The product of its digits is 22400, while the sum is 32.

The square root of 21745544 is about 4663.2117687276. The cubic root of 21745544 is about 279.1194445807.

The spelling of 21745544 in words is "twenty-one million, seven hundred forty-five thousand, five hundred forty-four".