18205851689 has 2 divisors, whose sum is σ = 18205851690. Its totient is φ = 18205851688.

The previous prime is 18205851679. The next prime is 18205851691. The reversal of 18205851689 is 98615850281.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15746485225 + 2459366464 = 125485^2 + 49592^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18205851689 is a prime.

It is a super-4 number, since 4×18205851689⁴ (a number of 42 digits) contains 4444 as substring.

Together with 18205851691, it forms a pair of twin primes.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 18205851689.

It is not a weakly prime, because it can be changed into another prime (18205851619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9102925844 + 9102925845.

It is an arithmetic number, because the mean of its divisors is an integer number (9102925845).

Almost surely, 2^18205851689 is an apocalyptic number.

It is an amenable number.

18205851689 is a deficient number, since it is larger than the sum of its proper divisors (1).

18205851689 is an equidigital number, since it uses as much as digits as its factorization.

18205851689 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1382400, while the sum is 53.

The spelling of 18205851689 in words is "eighteen billion, two hundred five million, eight hundred fifty-one thousand, six hundred eighty-nine".