28109869 has 2 divisors, whose sum is σ = 28109870. Its totient is φ = 28109868.

The previous prime is 28109867. The next prime is 28109897. The reversal of 28109869 is 96890182.

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., 21734244 + 6375625 = 4662^2 + 2525^2 .

It is a cyclic number.

It is not a de Polignac number, because 28109869 - 2¹ = 28109867 is a prime.

It is a super-2 number, since 2×28109869² = 1580329470394322, which contains 22 as substring.

Together with 28109867, 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 (28109867) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14054934 + 14054935.

It is an arithmetic number, because the mean of its divisors is an integer number (14054935).

Almost surely, 2^28109869 is an apocalyptic number.

It is an amenable number.

28109869 is a deficient number, since it is larger than the sum of its proper divisors (1).

28109869 is an equidigital number, since it uses as much as digits as its factorization.

28109869 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 62208, while the sum is 43.

The square root of 28109869 is about 5301.8741026169. The cubic root of 28109869 is about 304.0555538189.

The spelling of 28109869 in words is "twenty-eight million, one hundred nine thousand, eight hundred sixty-nine".