1812787491791 has 16 divisors (see below), whose sum is σ = 1935439334400. Its totient is φ = 1692886661568.

The previous prime is 1812787491737. The next prime is 1812787491841. The reversal of 1812787491791 is 1971947872181.

It is a cyclic number.

It is not a de Polignac number, because 1812787491791 - 2³⁸ = 1537909584847 is a prime.

It is a Smith number, since the sum of its digits (65) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1812787491191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2068220 + ... + 2811246.

It is an arithmetic number, because the mean of its divisors is an integer number (120964958400).

Almost surely, 2^{1812787491791} is an apocalyptic number.

1812787491791 is a deficient number, since it is larger than the sum of its proper divisors (122651842609).

1812787491791 is a wasteful number, since it uses less digits than its factorization.

1812787491791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 744878.

The product of its digits is 14224896, while the sum is 65.

The spelling of 1812787491791 in words is "one trillion, eight hundred twelve billion, seven hundred eighty-seven million, four hundred ninety-one thousand, seven hundred ninety-one".