21644243276 has 24 divisors (see below), whose sum is σ = 40156023936. Its totient is φ = 10189964160.

The previous prime is 21644243237. The next prime is 21644243329. The reversal of 21644243276 is 67234244612.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2354201 + ... + 2363376.

It is an arithmetic number, because the mean of its divisors is an integer number (1673167664).

Almost surely, 2^21644243276 is an apocalyptic number.

It is an amenable number.

21644243276 is a deficient number, since it is larger than the sum of its proper divisors (18511780660).

21644243276 is a wasteful number, since it uses less digits than its factorization.

21644243276 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4717649 (or 4717647 counting only the distinct ones).

The product of its digits is 387072, while the sum is 41.

Adding to 21644243276 its reverse (67234244612), we get a palindrome (88878487888).

The spelling of 21644243276 in words is "twenty-one billion, six hundred forty-four million, two hundred forty-three thousand, two hundred seventy-six".