1991575757824 has 33 divisors (see below), whose sum is σ = 3981296894241. Its totient is φ = 995765299200.

The previous prime is 1991575757789. The next prime is 1991575757833. The reversal of 1991575757824 is 4287575751991.

The square root of 1991575757824 is 1411232.

It is a perfect power (a square), and thus also a powerful number.

It can be written as a sum of positive squares in only one way, i.e., 1991395124224 + 180633600 = 1411168^2 + 13440^2 .

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 45137374 + ... + 45181474.

Almost surely, 2^{1991575757824} is an apocalyptic number.

1991575757824 is the 1411232-nd square number.

It is an amenable number.

1991575757824 is a deficient number, since it is larger than the sum of its proper divisors (1989721136417).

1991575757824 is an frugal number, since it uses more digits than its factorization.

1991575757824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 88222 (or 44103 counting only the distinct ones).

The product of its digits is 222264000, while the sum is 70.

The spelling of 1991575757824 in words is "one trillion, nine hundred ninety-one billion, five hundred seventy-five million, seven hundred fifty-seven thousand, eight hundred twenty-four".