19781359547897 has 4 divisors (see below), whose sum is σ = 19782405480180. Its totient is φ = 19780313615616.

The previous prime is 19781359547867. The next prime is 19781359547923. The reversal of 19781359547897 is 79874595318791.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12580208765881 + 7201150782016 = 3546859^2 + 2683496^2 .

It is a cyclic number.

It is not a de Polignac number, because 19781359547897 - 2¹² = 19781359543801 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19781359547837) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 522937772 + ... + 522975597.

It is an arithmetic number, because the mean of its divisors is an integer number (4945601370045).

Almost surely, 2^{19781359547897} is an apocalyptic number.

It is an amenable number.

19781359547897 is a deficient number, since it is larger than the sum of its proper divisors (1045932283).

19781359547897 is a wasteful number, since it uses less digits than its factorization.

19781359547897 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1045932282.

The product of its digits is 4800902400, while the sum is 83.

The spelling of 19781359547897 in words is "nineteen trillion, seven hundred eighty-one billion, three hundred fifty-nine million, five hundred forty-seven thousand, eight hundred ninety-seven".