28339781 has 2 divisors, whose sum is σ = 28339782. Its totient is φ = 28339780.

The previous prime is 28339771. The next prime is 28339813. The reversal of 28339781 is 18793382.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17056900 + 11282881 = 4130^2 + 3359^2 .

It is a cyclic number.

It is not a de Polignac number, because 28339781 - 2¹⁴ = 28323397 is a prime.

It is a super-2 number, since 2×28339781² = 1606286374255922, which contains 22 as substring.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28339711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14169890 + 14169891.

It is an arithmetic number, because the mean of its divisors is an integer number (14169891).

Almost surely, 2^28339781 is an apocalyptic number.

It is an amenable number.

28339781 is a deficient number, since it is larger than the sum of its proper divisors (1).

28339781 is an equidigital number, since it uses as much as digits as its factorization.

28339781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 72576, while the sum is 41.

The square root of 28339781 is about 5323.5120925945. The cubic root of 28339781 is about 304.8822657655.

The spelling of 28339781 in words is "twenty-eight million, three hundred thirty-nine thousand, seven hundred eighty-one".