28220311 has 4 divisors (see below), whose sum is σ = 32251792. Its totient is φ = 24188832.

The previous prime is 28220273. The next prime is 28220317. The reversal of 28220311 is 11302282.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 11302282 = 2 ⋅5651141.

It is a cyclic number.

It is not a de Polignac number, because 28220311 - 2¹⁵ = 28187543 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 (28220317) 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, 2015730 + ... + 2015743.

It is an arithmetic number, because the mean of its divisors is an integer number (8062948).

Almost surely, 2^28220311 is an apocalyptic number.

28220311 is a deficient number, since it is larger than the sum of its proper divisors (4031481).

28220311 is an equidigital number, since it uses as much as digits as its factorization.

28220311 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4031480.

The product of its (nonzero) digits is 192, while the sum is 19.

The square root of 28220311 is about 5312.2792660025. The cubic root of 28220311 is about 304.4532388291.

Adding to 28220311 its reverse (11302282), we get a palindrome (39522593).

The spelling of 28220311 in words is "twenty-eight million, two hundred twenty thousand, three hundred eleven".