1991603774591 has 8 divisors (see below), whose sum is σ = 2045595130704. Its totient is φ = 1937621062080.

The previous prime is 1991603774527. The next prime is 1991603774609. The reversal of 1991603774591 is 1954773061991.

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 1991603774591 - 2⁶ = 1991603774527 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 (1991603774291) 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, 1692470 + ... + 2616803.

It is an arithmetic number, because the mean of its divisors is an integer number (255699391338).

Almost surely, 2^{1991603774591} is an apocalyptic number.

1991603774591 is a deficient number, since it is larger than the sum of its proper divisors (53991356113).

1991603774591 is a wasteful number, since it uses less digits than its factorization.

1991603774591 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4321801.

The product of its (nonzero) digits is 12859560, while the sum is 62.

The spelling of 1991603774591 in words is "one trillion, nine hundred ninety-one billion, six hundred three million, seven hundred seventy-four thousand, five hundred ninety-one".