1991288381746 has 8 divisors (see below), whose sum is σ = 2988477809964. Its totient is φ = 995129111760.

The previous prime is 1991288381743. The next prime is 1991288381783. The reversal of 1991288381746 is 6471838821991.

It can be written as a sum of positive squares in 2 ways, for example, as 1593121071721 + 398167310025 = 1262189^2 + 631005^2 .

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

It is not an unprimeable number, because it can be changed into a prime (1991288381741) 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, 257534725 + ... + 257542456.

Almost surely, 2^{1991288381746} is an apocalyptic number.

1991288381746 is a deficient number, since it is larger than the sum of its proper divisors (997189428218).

1991288381746 is a wasteful number, since it uses less digits than its factorization.

1991288381746 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 515079116.

The product of its digits is 41803776, while the sum is 67.

The spelling of 1991288381746 in words is "one trillion, nine hundred ninety-one billion, two hundred eighty-eight million, three hundred eighty-one thousand, seven hundred forty-six".