6991203138121 has 2 divisors, whose sum is σ = 6991203138122. Its totient is φ = 6991203138120.

The previous prime is 6991203138103. The next prime is 6991203138163. The reversal of 6991203138121 is 1218313021996.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 4697080925625 + 2294122212496 = 2167275^2 + 1514636^2 .

It is a cyclic number.

It is not a de Polignac number, because 6991203138121 - 2⁷ = 6991203137993 is a prime.

It is not a weakly prime, because it can be changed into another prime (6991203138221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3495601569060 + 3495601569061.

It is an arithmetic number, because the mean of its divisors is an integer number (3495601569061).

Almost surely, 2^{6991203138121} is an apocalyptic number.

It is an amenable number.

6991203138121 is a deficient number, since it is larger than the sum of its proper divisors (1).

6991203138121 is an equidigital number, since it uses as much as digits as its factorization.

6991203138121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 139968, while the sum is 46.

The spelling of 6991203138121 in words is "six trillion, nine hundred ninety-one billion, two hundred three million, one hundred thirty-eight thousand, one hundred twenty-one".