991342658681 has 2 divisors, whose sum is σ = 991342658682. Its totient is φ = 991342658680.

The previous prime is 991342658651. The next prime is 991342658723. The reversal of 991342658681 is 186856243199.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 800146351081 + 191196307600 = 894509^2 + 437260^2 .

It is a cyclic number.

It is not a de Polignac number, because 991342658681 - 2¹⁸ = 991342396537 is a prime.

It is a super-2 number, since 2×991342658681² (a number of 25 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (991342658651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495671329340 + 495671329341.

It is an arithmetic number, because the mean of its divisors is an integer number (495671329341).

Almost surely, 2^991342658681 is an apocalyptic number.

It is an amenable number.

991342658681 is a deficient number, since it is larger than the sum of its proper divisors (1).

991342658681 is an equidigital number, since it uses as much as digits as its factorization.

991342658681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 22394880, while the sum is 62.

The spelling of 991342658681 in words is "nine hundred ninety-one billion, three hundred forty-two million, six hundred fifty-eight thousand, six hundred eighty-one".