21644081744 has 20 divisors (see below), whose sum is σ = 41962150560. Its totient is φ = 10815139680.

The previous prime is 21644081731. The next prime is 21644081761. The reversal of 21644081744 is 44718044612.

It is a happy number.

It is a congruent number.

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, 405404 + ... + 455675.

It is an arithmetic number, because the mean of its divisors is an integer number (2098107528).

Almost surely, 2^21644081744 is an apocalyptic number.

It is an amenable number.

21644081744 is a deficient number, since it is larger than the sum of its proper divisors (20318068816).

21644081744 is a wasteful number, since it uses less digits than its factorization.

21644081744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 862658 (or 862652 counting only the distinct ones).

The product of its (nonzero) digits is 172032, while the sum is 41.

The spelling of 21644081744 in words is "twenty-one billion, six hundred forty-four million, eighty-one thousand, seven hundred forty-four".