21778535659 has 4 divisors (see below), whose sum is σ = 21812197104. Its totient is φ = 21744874216.

The previous prime is 21778535621. The next prime is 21778535683. The reversal of 21778535659 is 95653587712.

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 21778535659 - 2¹⁵ = 21778502891 is a prime.

It is a Smith number, since the sum of its digits (58) 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 not an unprimeable number, because it can be changed into a prime (21778539659) 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, 16829752 + ... + 16831045.

It is an arithmetic number, because the mean of its divisors is an integer number (5453049276).

Almost surely, 2^21778535659 is an apocalyptic number.

21778535659 is a deficient number, since it is larger than the sum of its proper divisors (33661445).

21778535659 is an equidigital number, since it uses as much as digits as its factorization.

21778535659 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33661444.

The product of its digits is 15876000, while the sum is 58.

The spelling of 21778535659 in words is "twenty-one billion, seven hundred seventy-eight million, five hundred thirty-five thousand, six hundred fifty-nine".