991199109919 has 2 divisors, whose sum is σ = 991199109920. Its totient is φ = 991199109918.

The previous prime is 991199109893. The next prime is 991199109973. The reversal of 991199109919 is 919901991199.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 991199109919 - 2³¹ = 989051626271 is a prime.

It is a super-2 number, since 2×991199109919² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (991199109619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495599554959 + 495599554960.

It is an arithmetic number, because the mean of its divisors is an integer number (495599554960).

Almost surely, 2^991199109919 is an apocalyptic number.

991199109919 is a deficient number, since it is larger than the sum of its proper divisors (1).

991199109919 is an equidigital number, since it uses as much as digits as its factorization.

991199109919 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4782969, while the sum is 67.

The spelling of 991199109919 in words is "nine hundred ninety-one billion, one hundred ninety-nine million, one hundred nine thousand, nine hundred nineteen".