18661439149 has 2 divisors, whose sum is σ = 18661439150. Its totient is φ = 18661439148.

The previous prime is 18661439143. The next prime is 18661439221. The reversal of 18661439149 is 94193416681.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13490822500 + 5170616649 = 116150^2 + 71907^2 .

It is a cyclic number.

It is not a de Polignac number, because 18661439149 - 2⁹ = 18661438637 is a prime.

It is a super-2 number, since 2×18661439149² (a number of 21 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 18661439096 and 18661439105.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18661439143) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9330719574 + 9330719575.

It is an arithmetic number, because the mean of its divisors is an integer number (9330719575).

Almost surely, 2^18661439149 is an apocalyptic number.

It is an amenable number.

18661439149 is a deficient number, since it is larger than the sum of its proper divisors (1).

18661439149 is an equidigital number, since it uses as much as digits as its factorization.

18661439149 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1119744, while the sum is 52.

The spelling of 18661439149 in words is "eighteen billion, six hundred sixty-one million, four hundred thirty-nine thousand, one hundred forty-nine".