19806704640 has 264 divisors, whose sum is σ = 68966132040. Its totient is φ = 5255921664.

The previous prime is 19806704597. The next prime is 19806704647. The reversal of 19806704640 is 4640760891.

It can be written as a sum of positive squares in 4 ways, for example, as 7169347584 + 12637357056 = 84672^2 + 112416^2 .

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19806704647) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 10551382 + ... + 10553258.

Almost surely, 2^19806704640 is an apocalyptic number.

19806704640 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 19806704640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34483066020).

19806704640 is an abundant number, since it is smaller than the sum of its proper divisors (49159427400).

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

19806704640 is a wasteful number, since it uses less digits than its factorization.

19806704640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2137 (or 2116 counting only the distinct ones).

The product of its (nonzero) digits is 290304, while the sum is 45.

The spelling of 19806704640 in words is "nineteen billion, eight hundred six million, seven hundred four thousand, six hundred forty".