1781186161 has 2 divisors, whose sum is σ = 1781186162. Its totient is φ = 1781186160.

The previous prime is 1781186149. The next prime is 1781186167. The reversal of 1781186161 is 1616811871.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1748912400 + 32273761 = 41820^2 + 5681^2 .

It is an emirp because it is prime and its reverse (1616811871) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1781186161 - 2⁵ = 1781186129 is a prime.

It is not a weakly prime, because it can be changed into another prime (1781186167) 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 as a sum of consecutive naturals, namely, 890593080 + 890593081.

It is an arithmetic number, because the mean of its divisors is an integer number (890593081).

Almost surely, 2^1781186161 is an apocalyptic number.

It is an amenable number.

1781186161 is a deficient number, since it is larger than the sum of its proper divisors (1).

1781186161 is an equidigital number, since it uses as much as digits as its factorization.

1781186161 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 16128, while the sum is 40.

The square root of 1781186161 is about 42204.1012343587. The cubic root of 1781186161 is about 1212.1874147418.

The spelling of 1781186161 in words is "one billion, seven hundred eighty-one million, one hundred eighty-six thousand, one hundred sixty-one".