21730366687 has 4 divisors (see below), whose sum is σ = 21731225400. Its totient is φ = 21729507976.

The previous prime is 21730366667. The next prime is 21730366717. The reversal of 21730366687 is 78666303712.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21730366687 - 2¹⁹ = 21729842399 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21730366687.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21730366607) 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, 390208 + ... + 442405.

It is an arithmetic number, because the mean of its divisors is an integer number (5432806350).

Almost surely, 2^21730366687 is an apocalyptic number.

21730366687 is a deficient number, since it is larger than the sum of its proper divisors (858713).

21730366687 is an equidigital number, since it uses as much as digits as its factorization.

21730366687 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 858712.

The product of its (nonzero) digits is 1524096, while the sum is 49.

The spelling of 21730366687 in words is "twenty-one billion, seven hundred thirty million, three hundred sixty-six thousand, six hundred eighty-seven".