28001691181 has 4 divisors (see below), whose sum is σ = 28031074812. Its totient is φ = 27972307552.

The previous prime is 28001691169. The next prime is 28001691187. The reversal of 28001691181 is 18119610082.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 19777921956 + 8223769225 = 140634^2 + 90685^2 .

It is a cyclic number.

It is not a de Polignac number, because 28001691181 - 2⁵ = 28001691149 is a prime.

It is a super-2 number, since 2×28001691181² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28001691181.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28001691187) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 14690386 + ... + 14692291.

It is an arithmetic number, because the mean of its divisors is an integer number (7007768703).

Almost surely, 2^28001691181 is an apocalyptic number.

It is an amenable number.

28001691181 is a deficient number, since it is larger than the sum of its proper divisors (29383631).

28001691181 is an equidigital number, since it uses as much as digits as its factorization.

28001691181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 29383630.

The product of its (nonzero) digits is 6912, while the sum is 37.

The spelling of 28001691181 in words is "twenty-eight billion, one million, six hundred ninety-one thousand, one hundred eighty-one".