181920019181 has 2 divisors, whose sum is σ = 181920019182. Its totient is φ = 181920019180.

The previous prime is 181920019153. The next prime is 181920019201. The reversal of 181920019181 is 181910029181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 135026116681 + 46893902500 = 367459^2 + 216550^2 .

It is an emirp because it is prime and its reverse (181910029181) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 181920019181 - 2¹⁰ = 181920018157 is a prime.

It is a super-2 number, since 2×181920019181² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (181920019111) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90960009590 + 90960009591.

It is an arithmetic number, because the mean of its divisors is an integer number (90960009591).

Almost surely, 2^181920019181 is an apocalyptic number.

It is an amenable number.

181920019181 is a deficient number, since it is larger than the sum of its proper divisors (1).

181920019181 is an equidigital number, since it uses as much as digits as its factorization.

181920019181 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10368, while the sum is 41.

It can be divided in two parts, 1819200 and 19181, that added together give a palindrome (1838381).

The spelling of 181920019181 in words is "one hundred eighty-one billion, nine hundred twenty million, nineteen thousand, one hundred eighty-one".