1991338566958 has 8 divisors (see below), whose sum is σ = 3216777685128. Its totient is φ = 919079338584.

The previous prime is 1991338566883. The next prime is 1991338567013. The reversal of 1991338566958 is 8596658331991.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 38294972416 + ... + 38294972467.

It is an arithmetic number, because the mean of its divisors is an integer number (402097210641).

Almost surely, 2^{1991338566958} is an apocalyptic number.

1991338566958 is a deficient number, since it is larger than the sum of its proper divisors (1225439118170).

1991338566958 is a wasteful number, since it uses less digits than its factorization.

1991338566958 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76589944898.

The product of its digits is 377913600, while the sum is 73.

The spelling of 1991338566958 in words is "one trillion, nine hundred ninety-one billion, three hundred thirty-eight million, five hundred sixty-six thousand, nine hundred fifty-eight".