991199966611 has 8 divisors (see below), whose sum is σ = 996810190848. Its totient is φ = 985594125000.

The previous prime is 991199966591. The next prime is 991199966621. The reversal of 991199966611 is 116669991199.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 991199966611 - 2¹⁷ = 991199835539 is a prime.

It is a Duffinian number.

It is a zygodrome in base 10.

It is not an unprimeable number, because it can be changed into a prime (991199966621) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 641515 + ... + 1547236.

It is an arithmetic number, because the mean of its divisors is an integer number (124601273856).

Almost surely, 2^991199966611 is an apocalyptic number.

991199966611 is the 445242-nd centered decagonal number.

991199966611 is a deficient number, since it is larger than the sum of its proper divisors (5610224237).

991199966611 is a wasteful number, since it uses less digits than its factorization.

991199966611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2191313.

The product of its digits is 12754584, while the sum is 67.

The spelling of 991199966611 in words is "nine hundred ninety-one billion, one hundred ninety-nine million, nine hundred sixty-six thousand, six hundred eleven".