19965856218 has 128 divisors (see below), whose sum is σ = 52160495616. Its totient is φ = 4943505600.

The previous prime is 19965856217. The next prime is 19965856247. The reversal of 19965856218 is 81265856991.

It is not an unprimeable number, because it can be changed into a prime (19965856213) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 949171 + ... + 969977.

It is an arithmetic number, because the mean of its divisors is an integer number (407503872).

Almost surely, 2^19965856218 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19965856218, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26080247808).

19965856218 is an abundant number, since it is smaller than the sum of its proper divisors (32194639398).

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

19965856218 is a wasteful number, since it uses less digits than its factorization.

19965856218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20928.

The product of its digits is 9331200, while the sum is 60.

The spelling of 19965856218 in words is "nineteen billion, nine hundred sixty-five million, eight hundred fifty-six thousand, two hundred eighteen".