28381820291 has 4 divisors (see below), whose sum is σ = 30961985784. Its totient is φ = 25801654800.

The previous prime is 28381820287. The next prime is 28381820293. The reversal of 28381820291 is 19202818382.

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

It is a cyclic number.

It is not a de Polignac number, because 28381820291 - 2² = 28381820287 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28381820293) 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, 1290082730 + ... + 1290082751.

It is an arithmetic number, because the mean of its divisors is an integer number (7740496446).

Almost surely, 2^28381820291 is an apocalyptic number.

28381820291 is a deficient number, since it is larger than the sum of its proper divisors (2580165493).

28381820291 is a wasteful number, since it uses less digits than its factorization.

28381820291 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2580165492.

The product of its (nonzero) digits is 110592, while the sum is 44.

The spelling of 28381820291 in words is "twenty-eight billion, three hundred eighty-one million, eight hundred twenty thousand, two hundred ninety-one".