28103868721 has 4 divisors (see below), whose sum is σ = 28110142192. Its totient is φ = 28097595252.

The previous prime is 28103868697. The next prime is 28103868731. The reversal of 28103868721 is 12786830182.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 28103868721 - 2²¹ = 28101771569 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28103868731) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3130011 + ... + 3138976.

It is an arithmetic number, because the mean of its divisors is an integer number (7027535548).

Almost surely, 2^28103868721 is an apocalyptic number.

It is an amenable number.

28103868721 is a deficient number, since it is larger than the sum of its proper divisors (6273471).

28103868721 is an equidigital number, since it uses as much as digits as its factorization.

28103868721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6273470.

The product of its (nonzero) digits is 258048, while the sum is 46.

The spelling of 28103868721 in words is "twenty-eight billion, one hundred three million, eight hundred sixty-eight thousand, seven hundred twenty-one".