1811985173 has 2 divisors, whose sum is σ = 1811985174. Its totient is φ = 1811985172.

The previous prime is 1811985151. The next prime is 1811985181. The reversal of 1811985173 is 3715891181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1182878449 + 629106724 = 34393^2 + 25082^2 .

It is an emirp because it is prime and its reverse (3715891181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1811985173 - 2¹⁰ = 1811984149 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1811985143) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 905992586 + 905992587.

It is an arithmetic number, because the mean of its divisors is an integer number (905992587).

Almost surely, 2^1811985173 is an apocalyptic number.

It is an amenable number.

1811985173 is a deficient number, since it is larger than the sum of its proper divisors (1).

1811985173 is an equidigital number, since it uses as much as digits as its factorization.

1811985173 is an evil number, because the sum of its binary digits is even.

The product of its digits is 60480, while the sum is 44.

The square root of 1811985173 is about 42567.4191489219. The cubic root of 1811985173 is about 1219.1342897622.

The spelling of 1811985173 in words is "one billion, eight hundred eleven million, nine hundred eighty-five thousand, one hundred seventy-three".