1991516476609 has 12 divisors (see below), whose sum is σ = 2195192006928. Its totient is φ = 1791804796800.

The previous prime is 1991516476589. The next prime is 1991516476619. The reversal of 1991516476609 is 9066746151991.

It is not a de Polignac number, because 1991516476609 - 2⁹ = 1991516476097 is a prime.

It is a super-2 number, since 2×1991516476609² (a number of 25 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1991516476619) 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 in 11 ways as a sum of consecutive naturals, for example, 9517447 + ... + 9724444.

It is an arithmetic number, because the mean of its divisors is an integer number (182932667244).

Almost surely, 2^{1991516476609} is an apocalyptic number.

It is an amenable number.

1991516476609 is a deficient number, since it is larger than the sum of its proper divisors (203675530319).

1991516476609 is an equidigital number, since it uses as much as digits as its factorization.

1991516476609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19242096 (or 19241999 counting only the distinct ones).

The product of its (nonzero) digits is 22044960, while the sum is 64.

The spelling of 1991516476609 in words is "one trillion, nine hundred ninety-one billion, five hundred sixteen million, four hundred seventy-six thousand, six hundred nine".