19781668368 has 400 divisors, whose sum is σ = 71869400064. Its totient is φ = 5103025920.

The previous prime is 19781668343. The next prime is 19781668369. The reversal of 19781668368 is 86386618791.

19781668368 is a `hidden beast` number, since 197 + 81 + 6 + 6 + 8 + 368 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (19781668369) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 16664671 + ... + 16665857.

Almost surely, 2^19781668368 is an apocalyptic number.

19781668368 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 19781668368, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35934700032).

19781668368 is an abundant number, since it is smaller than the sum of its proper divisors (52087731696).

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

19781668368 is a wasteful number, since it uses less digits than its factorization.

19781668368 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1392 (or 1377 counting only the distinct ones).

The product of its digits is 20901888, while the sum is 63.

The spelling of 19781668368 in words is "nineteen billion, seven hundred eighty-one million, six hundred sixty-eight thousand, three hundred sixty-eight".