19187721840 has 320 divisors, whose sum is σ = 73452441600. Its totient is φ = 4127477760.

The previous prime is 19187721809. The next prime is 19187721869. The reversal of 19187721840 is 4812778191.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a self number, because there is not a number n which added to its sum of digits gives 19187721840.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 1392585 + ... + 1406295.

It is an arithmetic number, because the mean of its divisors is an integer number (229538880).

Almost surely, 2^19187721840 is an apocalyptic number.

19187721840 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 19187721840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (36726220800).

19187721840 is an abundant number, since it is smaller than the sum of its proper divisors (54264719760).

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

19187721840 is a wasteful number, since it uses less digits than its factorization.

19187721840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13765 (or 13745 counting only the distinct ones).

The product of its (nonzero) digits is 225792, while the sum is 48.

The spelling of 19187721840 in words is "nineteen billion, one hundred eighty-seven million, seven hundred twenty-one thousand, eight hundred forty".