1991373143 has 8 divisors (see below), whose sum is σ = 2085861888. Its totient is φ = 1897543384.

The previous prime is 1991373091. The next prime is 1991373151. The reversal of 1991373143 is 3413731991.

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 1991373143 - 2¹⁸ = 1991110999 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1991373143.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991373173) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 158555 + ... + 170652.

It is an arithmetic number, because the mean of its divisors is an integer number (260732736).

Almost surely, 2^1991373143 is an apocalyptic number.

1991373143 is a deficient number, since it is larger than the sum of its proper divisors (94488745).

1991373143 is a wasteful number, since it uses less digits than its factorization.

1991373143 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 329493.

The product of its digits is 61236, while the sum is 41.

The square root of 1991373143 is about 44624.8041228194. The cubic root of 1991373143 is about 1258.1069125505.

The spelling of 1991373143 in words is "one billion, nine hundred ninety-one million, three hundred seventy-three thousand, one hundred forty-three".