991643666346199 has 4 divisors (see below), whose sum is σ = 1007900119892920. Its totient is φ = 975387212799480.

The previous prime is 991643666346197. The next prime is 991643666346241.

It is a happy number.

991643666346199 is nontrivially palindromic in base 10.

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 991643666346199 - 2¹ = 991643666346197 is a prime.

It is a super-2 number, since 2×991643666346199² (a number of 31 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (991643666346191) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8128226773269 + ... + 8128226773390.

It is an arithmetic number, because the mean of its divisors is an integer number (251975029973230).

Almost surely, 2^{991643666346199} is an apocalyptic number.

991643666346199 is a deficient number, since it is larger than the sum of its proper divisors (16256453546721).

991643666346199 is a wasteful number, since it uses less digits than its factorization.

991643666346199 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16256453546720.

The product of its digits is 7346640384, while the sum is 82.

The spelling of 991643666346199 in words is "nine hundred ninety-one trillion, six hundred forty-three billion, six hundred sixty-six million, three hundred forty-six thousand, one hundred ninety-nine".