18644181649 has 2 divisors, whose sum is σ = 18644181650. Its totient is φ = 18644181648.

The previous prime is 18644181631. The next prime is 18644181667. The reversal of 18644181649 is 94618144681.

It is a balanced prime because it is at equal distance from previous prime (18644181631) and next prime (18644181667).

It can be written as a sum of positive squares in only one way, i.e., 18548533249 + 95648400 = 136193^2 + 9780^2 .

It is an emirp because it is prime and its reverse (94618144681) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 18644181649 - 2⁹ = 18644181137 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 18644181596 and 18644181605.

It is not a weakly prime, because it can be changed into another prime (18644181679) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9322090824 + 9322090825.

It is an arithmetic number, because the mean of its divisors is an integer number (9322090825).

Almost surely, 2^18644181649 is an apocalyptic number.

It is an amenable number.

18644181649 is a deficient number, since it is larger than the sum of its proper divisors (1).

18644181649 is an equidigital number, since it uses as much as digits as its factorization.

18644181649 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1327104, while the sum is 52.

The spelling of 18644181649 in words is "eighteen billion, six hundred forty-four million, one hundred eighty-one thousand, six hundred forty-nine".