21111808664 has 64 divisors (see below), whose sum is σ = 40770203040. Its totient is φ = 10245058560.

The previous prime is 21111808657. The next prime is 21111808667. The reversal of 21111808664 is 46680811112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21111808667) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 30910067 + ... + 30910749.

Almost surely, 2^21111808664 is an apocalyptic number.

It is an amenable number.

21111808664 is a deficient number, since it is larger than the sum of its proper divisors (19658394376).

21111808664 is a wasteful number, since it uses less digits than its factorization.

21111808664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1500 (or 1496 counting only the distinct ones).

The product of its (nonzero) digits is 18432, while the sum is 38.

The spelling of 21111808664 in words is "twenty-one billion, one hundred eleven million, eight hundred eight thousand, six hundred sixty-four".