28205194991 has 4 divisors (see below), whose sum is σ = 28210751184. Its totient is φ = 28199638800.

The previous prime is 28205194973. The next prime is 28205195003. The reversal of 28205194991 is 19949150282.

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 28205194991 - 2²² = 28201000687 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28205194931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2770475 + ... + 2780636.

It is an arithmetic number, because the mean of its divisors is an integer number (7052687796).

Almost surely, 2^28205194991 is an apocalyptic number.

28205194991 is a deficient number, since it is larger than the sum of its proper divisors (5556193).

28205194991 is an equidigital number, since it uses as much as digits as its factorization.

28205194991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5556192.

The product of its (nonzero) digits is 466560, while the sum is 50.

The spelling of 28205194991 in words is "twenty-eight billion, two hundred five million, one hundred ninety-four thousand, nine hundred ninety-one".