2166706650991 has 4 divisors (see below), whose sum is σ = 2166846752232. Its totient is φ = 2166566549752.

The previous prime is 2166706650967. The next prime is 2166706651033. The reversal of 2166706650991 is 1990566076612.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 2166706650991 - 2¹⁷ = 2166706519919 is a prime.

It is a super-2 number, since 2×2166706650991² (a number of 25 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (58) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2166706650091) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 70027420 + ... + 70058353.

It is an arithmetic number, because the mean of its divisors is an integer number (541711688058).

Almost surely, 2^{2166706650991} is an apocalyptic number.

2166706650991 is a deficient number, since it is larger than the sum of its proper divisors (140101241).

2166706650991 is a wasteful number, since it uses less digits than its factorization.

2166706650991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 140101240.

The product of its (nonzero) digits is 7348320, while the sum is 58.

The spelling of 2166706650991 in words is "two trillion, one hundred sixty-six billion, seven hundred six million, six hundred fifty thousand, nine hundred ninety-one".