18181969849 has 2 divisors, whose sum is σ = 18181969850. Its totient is φ = 18181969848.

The previous prime is 18181969847. The next prime is 18181969873. The reversal of 18181969849 is 94896918181.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 10659530025 + 7522439824 = 103245^2 + 86732^2 .

It is a cyclic number.

It is not a de Polignac number, because 18181969849 - 2¹ = 18181969847 is a prime.

Together with 18181969847, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (18181969847) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9090984924 + 9090984925.

It is an arithmetic number, because the mean of its divisors is an integer number (9090984925).

Almost surely, 2^18181969849 is an apocalyptic number.

It is an amenable number.

18181969849 is a deficient number, since it is larger than the sum of its proper divisors (1).

18181969849 is an equidigital number, since it uses as much as digits as its factorization.

18181969849 is an evil number, because the sum of its binary digits is even.

The product of its digits is 8957952, while the sum is 64.

The spelling of 18181969849 in words is "eighteen billion, one hundred eighty-one million, nine hundred sixty-nine thousand, eight hundred forty-nine".