20665636867 has 4 divisors (see below), whose sum is σ = 20668827096. Its totient is φ = 20662446640.

The previous prime is 20665636837. The next prime is 20665636889. The reversal of 20665636867 is 76863656602.

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 20665636867 - 2¹¹ = 20665634819 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (20665636807) 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, 1585378 + ... + 1598359.

It is an arithmetic number, because the mean of its divisors is an integer number (5167206774).

Almost surely, 2^20665636867 is an apocalyptic number.

20665636867 is a deficient number, since it is larger than the sum of its proper divisors (3190229).

20665636867 is an equidigital number, since it uses as much as digits as its factorization.

20665636867 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3190228.

The product of its (nonzero) digits is 13063680, while the sum is 55.

The spelling of 20665636867 in words is "twenty billion, six hundred sixty-five million, six hundred thirty-six thousand, eight hundred sixty-seven".