18605821391 has 2 divisors, whose sum is σ = 18605821392. Its totient is φ = 18605821390.

The previous prime is 18605821373. The next prime is 18605821439. The reversal of 18605821391 is 19312850681.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 18605821391 - 2¹⁰ = 18605820367 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18605821321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9302910695 + 9302910696.

It is an arithmetic number, because the mean of its divisors is an integer number (9302910696).

Almost surely, 2^18605821391 is an apocalyptic number.

18605821391 is a deficient number, since it is larger than the sum of its proper divisors (1).

18605821391 is an equidigital number, since it uses as much as digits as its factorization.

18605821391 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 103680, while the sum is 44.

The spelling of 18605821391 in words is "eighteen billion, six hundred five million, eight hundred twenty-one thousand, three hundred ninety-one".