21544345220 has 12 divisors (see below), whose sum is σ = 45243125004. Its totient is φ = 8617738080.

The previous prime is 21544345201. The next prime is 21544345223. The reversal of 21544345220 is 2254344512.

It can be written as a sum of positive squares in 2 ways, for example, as 3661702144 + 17882643076 = 60512^2 + 133726^2 .

It is not an unprimeable number, because it can be changed into a prime (21544345223) 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, 538608611 + ... + 538608650.

It is an arithmetic number, because the mean of its divisors is an integer number (3770260417).

Almost surely, 2^21544345220 is an apocalyptic number.

21544345220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21544345220 is an abundant number, since it is smaller than the sum of its proper divisors (23698779784).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21544345220 is a wasteful number, since it uses less digits than its factorization.

21544345220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1077217270 (or 1077217268 counting only the distinct ones).

The product of its (nonzero) digits is 38400, while the sum is 32.

Adding to 21544345220 its reverse (2254344512), we get a palindrome (23798689732).

The spelling of 21544345220 in words is "twenty-one billion, five hundred forty-four million, three hundred forty-five thousand, two hundred twenty".