21144649744 has 15 divisors (see below), whose sum is σ = 40968885853. Its totient is φ = 10572034048.

The previous prime is 21144649741. The next prime is 21144649753. The reversal of 21144649744 is 44794644112.

The square root of 21144649744 is 145412.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 6037290000 + 15107359744 = 77700^2 + 122912^2 .

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21144649694 and 21144649703.

It is not an unprimeable number, because it can be changed into a prime (21144649741) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 563472 + ... + 599824.

Almost surely, 2^21144649744 is an apocalyptic number.

21144649744 is the 145412-nd square number.

It is an amenable number.

21144649744 is a deficient number, since it is larger than the sum of its proper divisors (19824236109).

21144649744 is an frugal number, since it uses more digits than its factorization.

21144649744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 72714 (or 36355 counting only the distinct ones).

The product of its digits is 774144, while the sum is 46.

The spelling of 21144649744 in words is "twenty-one billion, one hundred forty-four million, six hundred forty-nine thousand, seven hundred forty-four".