28539781 has 2 divisors, whose sum is σ = 28539782. Its totient is φ = 28539780.

The previous prime is 28539779. The next prime is 28539853. The reversal of 28539781 is 18793582.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17715681 + 10824100 = 4209^2 + 3290^2 .

It is a cyclic number.

It is not a de Polignac number, because 28539781 - 2¹ = 28539779 is a prime.

It is a super-2 number, since 2×28539781² = 1629038199055922, which contains 22 as substring.

Together with 28539779, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28539751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14269890 + 14269891.

It is an arithmetic number, because the mean of its divisors is an integer number (14269891).

Almost surely, 2^28539781 is an apocalyptic number.

It is an amenable number.

28539781 is a deficient number, since it is larger than the sum of its proper divisors (1).

28539781 is an equidigital number, since it uses as much as digits as its factorization.

28539781 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 120960, while the sum is 43.

The square root of 28539781 is about 5342.2636587873. The cubic root of 28539781 is about 305.5977920139.

The spelling of 28539781 in words is "twenty-eight million, five hundred thirty-nine thousand, seven hundred eighty-one".