21666036756 has 96 divisors (see below), whose sum is σ = 65495234560. Its totient is φ = 5413371264.

The previous prime is 21666036709. The next prime is 21666036779. The reversal of 21666036756 is 65763066612.

It is a hoax number, since the sum of its digits (48) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 501376 + ... + 542871.

Almost surely, 2^21666036756 is an apocalyptic number.

21666036756 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

It is an amenable number.

21666036756 is an abundant number, since it is smaller than the sum of its proper divisors (43829197804).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21666036756 is a wasteful number, since it uses less digits than its factorization.

21666036756 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1044293 (or 1044291 counting only the distinct ones).

The product of its (nonzero) digits is 1632960, while the sum is 48.

The spelling of 21666036756 in words is "twenty-one billion, six hundred sixty-six million, thirty-six thousand, seven hundred fifty-six".