21544217768 has 16 divisors (see below), whose sum is σ = 40690267380. Its totient is φ = 10693479808.

The previous prime is 21544217719. The next prime is 21544217791. The reversal of 21544217768 is 86771244512.

It can be written as a sum of positive squares in 2 ways, for example, as 20868113764 + 676104004 = 144458^2 + 26002^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9827471 + ... + 9829662.

Almost surely, 2^21544217768 is an apocalyptic number.

It is an amenable number.

21544217768 is a deficient number, since it is larger than the sum of its proper divisors (19146049612).

21544217768 is a wasteful number, since it uses less digits than its factorization.

21544217768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19657276 (or 19657272 counting only the distinct ones).

The product of its digits is 752640, while the sum is 47.

The spelling of 21544217768 in words is "twenty-one billion, five hundred forty-four million, two hundred seventeen thousand, seven hundred sixty-eight".