19728704645 has 16 divisors (see below), whose sum is σ = 25601367792. Its totient is φ = 14508426240.

The previous prime is 19728704617. The next prime is 19728704647. The reversal of 19728704645 is 54640782791.

It can be written as a sum of positive squares in 8 ways, for example, as 1097000641 + 18631704004 = 33121^2 + 136498^2 .

It is not a de Polignac number, because 19728704645 - 2¹⁶ = 19728639109 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (19728704647) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 614042 + ... + 645371.

It is an arithmetic number, because the mean of its divisors is an integer number (1600085487).

Almost surely, 2^19728704645 is an apocalyptic number.

It is an amenable number.

19728704645 is a deficient number, since it is larger than the sum of its proper divisors (5872663147).

19728704645 is a wasteful number, since it uses less digits than its factorization.

19728704645 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1259672.

The product of its (nonzero) digits is 3386880, while the sum is 53.

The spelling of 19728704645 in words is "nineteen billion, seven hundred twenty-eight million, seven hundred four thousand, six hundred forty-five".