19399540969081 has 81 divisors (see below), whose sum is σ = 25323111314631. Its totient is φ = 14810929031808.

The previous prime is 19399540969033. The next prime is 19399540969111. The reversal of 19399540969081 is 18096904599391.

The square root of 19399540969081 is 4404491.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in 13 ways, for example, as 15688847637225 + 3710693331856 = 3960915^2 + 1926316^2 .

It is not a de Polignac number, because 19399540969081 - 2¹⁵ = 19399540936313 is a prime.

It is a super-2 number, since 2×19399540969081² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 19399540968995 and 19399540969013.

It is not an unprimeable number, because it can be changed into a prime (19399540964081) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 11623450915 + ... + 11623452583.

Almost surely, 2^{19399540969081} is an apocalyptic number.

19399540969081 is the 4404491-st square number.

19399540969081 is the 2202246-th centered octagonal number.

It is an amenable number.

19399540969081 is a deficient number, since it is larger than the sum of its proper divisors (5923570345550).

19399540969081 is an frugal number, since it uses more digits than its factorization.

19399540969081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3436 (or 1718 counting only the distinct ones).

The product of its (nonzero) digits is 170061120, while the sum is 73.

The spelling of 19399540969081 in words is "nineteen trillion, three hundred ninety-nine billion, five hundred forty million, nine hundred sixty-nine thousand, eighty-one".