19961434665 has 40 divisors (see below), whose sum is σ = 35811416520. Its totient is φ = 10637561088.

The previous prime is 19961434643. The next prime is 19961434699. The reversal of 19961434665 is 56643416991.

It is a happy number.

19961434665 is a `hidden beast` number, since 1 + 99 + 61 + 434 + 6 + 65 = 666.

It can be written as a sum of positive squares in 4 ways, for example, as 4493289024 + 15468145641 = 67032^2 + 124371^2 .

It is not a de Polignac number, because 19961434665 - 2⁶ = 19961434601 is a prime.

It is a super-3 number, since 3×19961434665³ (a number of 32 digits) contains 333 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 502927 + ... + 541163.

It is an arithmetic number, because the mean of its divisors is an integer number (895285413).

Almost surely, 2^19961434665 is an apocalyptic number.

19961434665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

19961434665 is a deficient number, since it is larger than the sum of its proper divisors (15849981855).

19961434665 is a wasteful number, since it uses less digits than its factorization.

19961434665 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 39543 (or 39534 counting only the distinct ones).

The product of its digits is 4199040, while the sum is 54.

The spelling of 19961434665 in words is "nineteen billion, nine hundred sixty-one million, four hundred thirty-four thousand, six hundred sixty-five".