18306743821 has 2 divisors, whose sum is σ = 18306743822. Its totient is φ = 18306743820.

The previous prime is 18306743797. The next prime is 18306743837. The reversal of 18306743821 is 12834760381.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12953626596 + 5353117225 = 113814^2 + 73165^2 .

It is a cyclic number.

It is not a de Polignac number, because 18306743821 - 2⁹ = 18306743309 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18306743881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9153371910 + 9153371911.

It is an arithmetic number, because the mean of its divisors is an integer number (9153371911).

Almost surely, 2^18306743821 is an apocalyptic number.

It is an amenable number.

18306743821 is a deficient number, since it is larger than the sum of its proper divisors (1).

18306743821 is an equidigital number, since it uses as much as digits as its factorization.

18306743821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 193536, while the sum is 43.

The spelling of 18306743821 in words is "eighteen billion, three hundred six million, seven hundred forty-three thousand, eight hundred twenty-one".