1991676745 has 4 divisors (see below), whose sum is σ = 2390012100. Its totient is φ = 1593341392.

The previous prime is 1991676727. The next prime is 1991676749. The reversal of 1991676745 is 5476761991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5476761991 = 68113 ⋅80407.

It can be written as a sum of positive squares in 2 ways, for example, as 1130371641 + 861305104 = 33621^2 + 29348^2 .

It is a cyclic number.

It is not a de Polignac number, because 1991676745 - 2¹⁵ = 1991643977 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1991676749) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 199167670 + ... + 199167679.

It is an arithmetic number, because the mean of its divisors is an integer number (597503025).

Almost surely, 2^1991676745 is an apocalyptic number.

It is an amenable number.

1991676745 is a deficient number, since it is larger than the sum of its proper divisors (398335355).

1991676745 is an equidigital number, since it uses as much as digits as its factorization.

1991676745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 398335354.

The product of its digits is 2857680, while the sum is 55.

The square root of 1991676745 is about 44628.2057111867. The cubic root of 1991676745 is about 1258.1708457159.

The spelling of 1991676745 in words is "one billion, nine hundred ninety-one million, six hundred seventy-six thousand, seven hundred forty-five".