1811961181 has 2 divisors, whose sum is σ = 1811961182. Its totient is φ = 1811961180.

The previous prime is 1811961161. The next prime is 1811961211. The reversal of 1811961181 is 1811691181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 963171225 + 848789956 = 31035^2 + 29134^2 .

It is a cyclic number.

It is not a de Polignac number, because 1811961181 - 2¹⁵ = 1811928413 is a prime.

It is a super-2 number, since 2×1811961181² = 6566406642901829522, which contains 22 as substring.

1811961181 is a strobogrammatic number because it is the same when read upside-down.

It is a self number, because there is not a number n which added to its sum of digits gives 1811961181.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1811961101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 905980590 + 905980591.

It is an arithmetic number, because the mean of its divisors is an integer number (905980591).

Almost surely, 2^1811961181 is an apocalyptic number.

It is an amenable number.

1811961181 is a deficient number, since it is larger than the sum of its proper divisors (1).

1811961181 is an equidigital number, since it uses as much as digits as its factorization.

1811961181 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3456, while the sum is 37.

The square root of 1811961181 is about 42567.1373362128. The cubic root of 1811961181 is about 1219.1289089973.

The spelling of 1811961181 in words is "one billion, eight hundred eleven million, nine hundred sixty-one thousand, one hundred eighty-one".