12173687821 has 2 divisors, whose sum is σ = 12173687822. Its totient is φ = 12173687820.

The previous prime is 12173687753. The next prime is 12173687837. The reversal of 12173687821 is 12878637121.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 9039255625 + 3134432196 = 95075^2 + 55986^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-12173687821 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (12173687621) 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, 6086843910 + 6086843911.

It is an arithmetic number, because the mean of its divisors is an integer number (6086843911).

Almost surely, 2^12173687821 is an apocalyptic number.

It is an amenable number.

12173687821 is a deficient number, since it is larger than the sum of its proper divisors (1).

12173687821 is an equidigital number, since it uses as much as digits as its factorization.

12173687821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 225792, while the sum is 46.

The spelling of 12173687821 in words is "twelve billion, one hundred seventy-three million, six hundred eighty-seven thousand, eight hundred twenty-one".