21666809703 has 48 divisors (see below), whose sum is σ = 36367009280. Its totient is φ = 11231732160.

The previous prime is 21666809699. The next prime is 21666809707. The reversal of 21666809703 is 30790866612.

It is an interprime number because it is at equal distance from previous prime (21666809699) and next prime (21666809707).

It is not a de Polignac number, because 21666809703 - 2² = 21666809699 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21666809707) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1228713 + ... + 1246221.

Almost surely, 2^21666809703 is an apocalyptic number.

21666809703 is a deficient number, since it is larger than the sum of its proper divisors (14700199577).

21666809703 is a wasteful number, since it uses less digits than its factorization.

21666809703 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 18028 (or 18017 counting only the distinct ones).

The product of its (nonzero) digits is 653184, while the sum is 48.

The spelling of 21666809703 in words is "twenty-one billion, six hundred sixty-six million, eight hundred nine thousand, seven hundred three".