1811621781133 has 2 divisors, whose sum is σ = 1811621781134. Its totient is φ = 1811621781132.

The previous prime is 1811621781127. The next prime is 1811621781239. The reversal of 1811621781133 is 3311871261181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1556538197769 + 255083583364 = 1247613^2 + 505058^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1811621781133 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1811621781133.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1811621751133) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 905810890566 + 905810890567.

It is an arithmetic number, because the mean of its divisors is an integer number (905810890567).

Almost surely, 2^{1811621781133} is an apocalyptic number.

It is an amenable number.

1811621781133 is a deficient number, since it is larger than the sum of its proper divisors (1).

1811621781133 is an equidigital number, since it uses as much as digits as its factorization.

1811621781133 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 48384, while the sum is 43.

The spelling of 1811621781133 in words is "one trillion, eight hundred eleven billion, six hundred twenty-one million, seven hundred eighty-one thousand, one hundred thirty-three".