28288681 has 2 divisors, whose sum is σ = 28288682. Its totient is φ = 28288680.

The previous prime is 28288679. The next prime is 28288691. The reversal of 28288681 is 18688282.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 23040000 + 5248681 = 4800^2 + 2291^2 .

It is a cyclic number.

It is not a de Polignac number, because 28288681 - 2¹ = 28288679 is a prime.

It is a super-2 number, since 2×28288681² = 1600498945439522, which contains 22 as substring.

Together with 28288679, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (28288621) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14144340 + 14144341.

It is an arithmetic number, because the mean of its divisors is an integer number (14144341).

Almost surely, 2^28288681 is an apocalyptic number.

It is an amenable number.

28288681 is a deficient number, since it is larger than the sum of its proper divisors (1).

28288681 is an equidigital number, since it uses as much as digits as its factorization.

28288681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 98304, while the sum is 43.

The square root of 28288681 is about 5318.7104640129. The cubic root of 28288681 is about 304.6989091726.

The spelling of 28288681 in words is "twenty-eight million, two hundred eighty-eight thousand, six hundred eighty-one".