16665968991 has 16 divisors (see below), whose sum is σ = 25399713024. Its totient is φ = 9521929344.

The previous prime is 16665968971. The next prime is 16665969011. The reversal of 16665968991 is 19986956661.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (16665968971) and next prime (16665969011).

It is not a de Polignac number, because 16665968991 - 2²² = 16661774687 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16665968911) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 84535 + ... + 201191.

It is an arithmetic number, because the mean of its divisors is an integer number (1587482064).

Almost surely, 2^16665968991 is an apocalyptic number.

16665968991 is a deficient number, since it is larger than the sum of its proper divisors (8733744033).

16665968991 is a wasteful number, since it uses less digits than its factorization.

16665968991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123470.

The product of its digits is 37791360, while the sum is 66.

The spelling of 16665968991 in words is "sixteen billion, six hundred sixty-five million, nine hundred sixty-eight thousand, nine hundred ninety-one".