19965338491081 has 9 divisors (see below), whose sum is σ = 20440643309319. Its totient is φ = 19500840626736.

The previous prime is 19965338491073. The next prime is 19965338491093. The reversal of 19965338491081 is 18019483356991.

It is a happy number.

The square root of 19965338491081 is 4468259.

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

It can be written as a sum of positive squares in only one way, i.e., 3588618753225 + 16376719737856 = 1894365^2 + 4046816^2 .

It is not a de Polignac number, because 19965338491081 - 2³ = 19965338491073 is a prime.

It is a super-2 number, since 2×19965338491081² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 19965338490998 and 19965338491016.

It is not an unprimeable number, because it can be changed into a prime (19965338491051) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 192083181 + ... + 192187093.

Almost surely, 2^{19965338491081} is an apocalyptic number.

19965338491081 is the 4468259-th square number.

19965338491081 is the 2234130-th centered octagonal number.

It is an amenable number.

19965338491081 is a deficient number, since it is larger than the sum of its proper divisors (475304818238).

19965338491081 is an frugal number, since it uses more digits than its factorization.

19965338491081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 207912 (or 103956 counting only the distinct ones).

The product of its (nonzero) digits is 50388480, while the sum is 67.

The spelling of 19965338491081 in words is "nineteen trillion, nine hundred sixty-five billion, three hundred thirty-eight million, four hundred ninety-one thousand, eighty-one".