19881647645 has 8 divisors (see below), whose sum is σ = 25261387704. Its totient is φ = 14969711104.

The previous prime is 19881647641. The next prime is 19881647647. The reversal of 19881647645 is 54674618891.

It can be written as a sum of positive squares in 4 ways, for example, as 9978611449 + 9903036196 = 99893^2 + 99514^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 19881647645 - 2² = 19881647641 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19881647641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 116950784 + ... + 116950953.

It is an arithmetic number, because the mean of its divisors is an integer number (3157673463).

Almost surely, 2^19881647645 is an apocalyptic number.

It is an amenable number.

19881647645 is a deficient number, since it is larger than the sum of its proper divisors (5379740059).

19881647645 is a wasteful number, since it uses less digits than its factorization.

19881647645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 233901759.

The product of its digits is 11612160, while the sum is 59.

The spelling of 19881647645 in words is "nineteen billion, eight hundred eighty-one million, six hundred forty-seven thousand, six hundred forty-five".