17991842661 has 32 divisors (see below), whose sum is σ = 29315704320. Its totient is φ = 10836320832.

The previous prime is 17991842593. The next prime is 17991842677. The reversal of 17991842661 is 16624819971.

17991842661 is a `hidden beast` number, since 1 + 79 + 91 + 8 + 426 + 61 = 666.

It is not a de Polignac number, because 17991842661 - 2⁹ = 17991842149 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 17991842598 and 17991842607.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (17991842761) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 528810 + ... + 561803.

It is an arithmetic number, because the mean of its divisors is an integer number (916115760).

Almost surely, 2^17991842661 is an apocalyptic number.

It is an amenable number.

17991842661 is a deficient number, since it is larger than the sum of its proper divisors (11323861659).

17991842661 is a wasteful number, since it uses less digits than its factorization.

17991842661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1090682 (or 1090676 counting only the distinct ones).

The product of its digits is 1306368, while the sum is 54.

The spelling of 17991842661 in words is "seventeen billion, nine hundred ninety-one million, eight hundred forty-two thousand, six hundred sixty-one".