21668533996 has 12 divisors (see below), whose sum is σ = 37970975952. Its totient is φ = 10819683728.

The previous prime is 21668533993. The next prime is 21668534029. The reversal of 21668533996 is 69933586612.

It is a self number, because there is not a number n which added to its sum of digits gives 21668533996.

It is not an unprimeable number, because it can be changed into a prime (21668533993) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3642475 + ... + 3648418.

It is an arithmetic number, because the mean of its divisors is an integer number (3164247996).

Almost surely, 2^21668533996 is an apocalyptic number.

It is an amenable number.

21668533996 is a deficient number, since it is larger than the sum of its proper divisors (16302441956).

21668533996 is a wasteful number, since it uses less digits than its factorization.

21668533996 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7291640 (or 7291638 counting only the distinct ones).

The product of its digits is 12597120, while the sum is 58.

The spelling of 21668533996 in words is "twenty-one billion, six hundred sixty-eight million, five hundred thirty-three thousand, nine hundred ninety-six".