19681318440 has 864 divisors, whose sum is σ = 81586945440. Its totient is φ = 4252227840.

The previous prime is 19681318417. The next prime is 19681318457. The reversal of 19681318440 is 4481318691.

19681318440 is a `hidden beast` number, since 19 + 68 + 131 + 8 + 440 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

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 215 ways as a sum of consecutive naturals, for example, 457705059 + ... + 457705101.

It is an arithmetic number, because the mean of its divisors is an integer number (94429335).

Almost surely, 2^19681318440 is an apocalyptic number.

19681318440 is a gapful number since it is divisible by the number (10) 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 19681318440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (40793472720).

19681318440 is an abundant number, since it is smaller than the sum of its proper divisors (61905627000).

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

19681318440 is a wasteful number, since it uses less digits than its factorization.

19681318440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 145 (or 91 counting only the distinct ones).

The product of its (nonzero) digits is 165888, while the sum is 45.

The spelling of 19681318440 in words is "nineteen billion, six hundred eighty-one million, three hundred eighteen thousand, four hundred forty".