18331730877721 has 2 divisors, whose sum is σ = 18331730877722. Its totient is φ = 18331730877720.

The previous prime is 18331730877679. The next prime is 18331730877731. The reversal of 18331730877721 is 12777803713381.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15708254196496 + 2623476681225 = 3963364^2 + 1619715^2 .

It is a cyclic number.

It is not a de Polignac number, because 18331730877721 - 2¹⁷ = 18331730746649 is a prime.

It is not a weakly prime, because it can be changed into another prime (18331730877731) 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, 9165865438860 + 9165865438861.

It is an arithmetic number, because the mean of its divisors is an integer number (9165865438861).

Almost surely, 2^{18331730877721} is an apocalyptic number.

It is an amenable number.

18331730877721 is a deficient number, since it is larger than the sum of its proper divisors (1).

18331730877721 is an equidigital number, since it uses as much as digits as its factorization.

18331730877721 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8297856, while the sum is 58.

The spelling of 18331730877721 in words is "eighteen trillion, three hundred thirty-one billion, seven hundred thirty million, eight hundred seventy-seven thousand, seven hundred twenty-one".