1991816278199 has 8 divisors (see below), whose sum is σ = 2200395429120. Its totient is φ = 1787821284600.

The previous prime is 1991816278147. The next prime is 1991816278201. The reversal of 1991816278199 is 9918726181991.

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 1991816278199 - 2³⁶ = 1923096801463 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991816278799) 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, 1146038417 + ... + 1146040154.

It is an arithmetic number, because the mean of its divisors is an integer number (275049428640).

Almost surely, 2^{1991816278199} is an apocalyptic number.

1991816278199 is a deficient number, since it is larger than the sum of its proper divisors (208579150921).

1991816278199 is a wasteful number, since it uses less digits than its factorization.

1991816278199 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2292078661.

The product of its digits is 35271936, while the sum is 71.

The spelling of 1991816278199 in words is "one trillion, nine hundred ninety-one billion, eight hundred sixteen million, two hundred seventy-eight thousand, one hundred ninety-nine".