19901191681 has 32 divisors (see below), whose sum is σ = 24045120000. Its totient is φ = 16444967616.

The previous prime is 19901191663. The next prime is 19901191691. The reversal of 19901191681 is 18619110991.

It is not a de Polignac number, because 19901191681 - 2⁷ = 19901191553 is a prime.

It is a super-2 number, since 2×19901191681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (19901191631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 9617715 + ... + 9619783.

It is an arithmetic number, because the mean of its divisors is an integer number (751410000).

Almost surely, 2^19901191681 is an apocalyptic number.

It is an amenable number.

19901191681 is a deficient number, since it is larger than the sum of its proper divisors (4143928319).

19901191681 is an equidigital number, since it uses as much as digits as its factorization.

19901191681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3086 (or 3072 counting only the distinct ones).

The product of its (nonzero) digits is 34992, while the sum is 46.

The spelling of 19901191681 in words is "nineteen billion, nine hundred one million, one hundred ninety-one thousand, six hundred eighty-one".