18821657693 has 2 divisors, whose sum is σ = 18821657694. Its totient is φ = 18821657692.

The previous prime is 18821657641. The next prime is 18821657711. The reversal of 18821657693 is 39675612881.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17062106884 + 1759550809 = 130622^2 + 41947^2 .

It is a cyclic number.

It is not a de Polignac number, because 18821657693 - 2³² = 14526690397 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18821657293) 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, 9410828846 + 9410828847.

It is an arithmetic number, because the mean of its divisors is an integer number (9410828847).

Almost surely, 2^18821657693 is an apocalyptic number.

It is an amenable number.

18821657693 is a deficient number, since it is larger than the sum of its proper divisors (1).

18821657693 is an equidigital number, since it uses as much as digits as its factorization.

18821657693 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 4354560, while the sum is 56.

The spelling of 18821657693 in words is "eighteen billion, eight hundred twenty-one million, six hundred fifty-seven thousand, six hundred ninety-three".