28109811 has 4 divisors (see below), whose sum is σ = 37479752. Its totient is φ = 18739872.

The previous prime is 28109779. The next prime is 28109821. The reversal of 28109811 is 11890182.

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

It is not a de Polignac number, because 28109811 - 2⁵ = 28109779 is a prime.

It is a super-2 number, since 2×28109811² = 1580322948911442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (28109821) 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, 4684966 + ... + 4684971.

It is an arithmetic number, because the mean of its divisors is an integer number (9369938).

Almost surely, 2^28109811 is an apocalyptic number.

28109811 is a deficient number, since it is larger than the sum of its proper divisors (9369941).

28109811 is an equidigital number, since it uses as much as digits as its factorization.

28109811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9369940.

The product of its (nonzero) digits is 1152, while the sum is 30.

The square root of 28109811 is about 5301.8686328501. The cubic root of 28109811 is about 304.0553446962.

Adding to 28109811 its reverse (11890182), we get a palindrome (39999993).

It can be divided in two parts, 28109 and 811, that added together give a triangular number (28920 = T₂₄₀).

The spelling of 28109811 in words is "twenty-eight million, one hundred nine thousand, eight hundred eleven".