28238761 has 4 divisors (see below), whose sum is σ = 28279300. Its totient is φ = 28198224.

The previous prime is 28238741. The next prime is 28238767. The reversal of 28238761 is 16783282.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 16783282 = 2 ⋅8391641.

It can be written as a sum of positive squares in 2 ways, for example, as 15848361 + 12390400 = 3981^2 + 3520^2 .

It is a cyclic number.

It is not a de Polignac number, because 28238761 - 2⁵ = 28238729 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28238761.

It is not an unprimeable number, because it can be changed into a prime (28238767) 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, 19206 + ... + 20623.

It is an arithmetic number, because the mean of its divisors is an integer number (7069825).

Almost surely, 2^28238761 is an apocalyptic number.

28238761 is the 2377-th centered decagonal number.

It is an amenable number.

28238761 is a deficient number, since it is larger than the sum of its proper divisors (40539).

28238761 is an equidigital number, since it uses as much as digits as its factorization.

28238761 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40538.

The product of its digits is 32256, while the sum is 37.

The square root of 28238761 is about 5314.0155250055. The cubic root of 28238761 is about 304.5195733043.

The spelling of 28238761 in words is "twenty-eight million, two hundred thirty-eight thousand, seven hundred sixty-one".