28078121 has 2 divisors, whose sum is σ = 28078122. Its totient is φ = 28078120.

The previous prime is 28078111. The next prime is 28078123. The reversal of 28078121 is 12187082.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21752896 + 6325225 = 4664^2 + 2515^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28078121 is a prime.

Together with 28078123, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (28078123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14039060 + 14039061.

It is an arithmetic number, because the mean of its divisors is an integer number (14039061).

Almost surely, 2^28078121 is an apocalyptic number.

It is an amenable number.

28078121 is a deficient number, since it is larger than the sum of its proper divisors (1).

28078121 is an equidigital number, since it uses as much as digits as its factorization.

28078121 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1792, while the sum is 29.

The square root of 28078121 is about 5298.8792211184. The cubic root of 28078121 is about 303.9410413420.

The spelling of 28078121 in words is "twenty-eight million, seventy-eight thousand, one hundred twenty-one".