991199019919 has 2 divisors, whose sum is σ = 991199019920. Its totient is φ = 991199019918.

The previous prime is 991199019893. The next prime is 991199019971. The reversal of 991199019919 is 919910991199.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 991199019919 - 2²⁹ = 990662149007 is a prime.

It is a super-2 number, since 2×991199019919² (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 (991199019319) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 495599509959 + 495599509960.

It is an arithmetic number, because the mean of its divisors is an integer number (495599509960).

Almost surely, 2^991199019919 is an apocalyptic number.

991199019919 is a deficient number, since it is larger than the sum of its proper divisors (1).

991199019919 is an equidigital number, since it uses as much as digits as its factorization.

991199019919 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 991199019919 in words is "nine hundred ninety-one billion, one hundred ninety-nine million, nineteen thousand, nine hundred nineteen".