28728881 has 2 divisors, whose sum is σ = 28728882. Its totient is φ = 28728880.

The previous prime is 28728857. The next prime is 28728911. The reversal of 28728881 is 18882782.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 28718881 + 10000 = 5359^2 + 100^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28728881 is a prime.

It is a super-2 number, since 2×28728881² = 1650697207024322, which contains 22 as substring.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (28728851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14364440 + 14364441.

It is an arithmetic number, because the mean of its divisors is an integer number (14364441).

Almost surely, 2^28728881 is an apocalyptic number.

It is an amenable number.

28728881 is a deficient number, since it is larger than the sum of its proper divisors (1).

28728881 is an equidigital number, since it uses as much as digits as its factorization.

28728881 is an evil number, because the sum of its binary digits is even.

The product of its digits is 114688, while the sum is 44.

The square root of 28728881 is about 5359.9329286848. The cubic root of 28728881 is about 306.2712540573.

The spelling of 28728881 in words is "twenty-eight million, seven hundred twenty-eight thousand, eight hundred eighty-one".