991787949787199 has 2 divisors, whose sum is σ = 991787949787200. Its totient is φ = 991787949787198.

The previous prime is 991787949787189. The next prime is 991787949787303.

991787949787199 is nontrivially palindromic in base 10.

It is an a-pointer prime, because the next prime (991787949787303) can be obtained adding 991787949787199 to its sum of digits (104).

It is a weak prime.

It is a palprime.

It is a cyclic number.

It is not a de Polignac number, because 991787949787199 - 2⁴⁰ = 990688438159423 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991787949787189) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495893974893599 + 495893974893600.

It is an arithmetic number, because the mean of its divisors is an integer number (495893974893600).

Almost surely, 2^{991787949787199} is an apocalyptic number.

991787949787199 is a deficient number, since it is larger than the sum of its proper divisors (1).

991787949787199 is an equidigital number, since it uses as much as digits as its factorization.

991787949787199 is an evil number, because the sum of its binary digits is even.

The product of its digits is 326653399296, while the sum is 104.

The spelling of 991787949787199 in words is "nine hundred ninety-one trillion, seven hundred eighty-seven billion, nine hundred forty-nine million, seven hundred eighty-seven thousand, one hundred ninety-nine".