28190861 has 2 divisors, whose sum is σ = 28190862. Its totient is φ = 28190860.

The previous prime is 28190857. The next prime is 28190863. The reversal of 28190861 is 16809182.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 23377225 + 4813636 = 4835^2 + 2194^2 .

It is a cyclic number.

It is not a de Polignac number, because 28190861 - 2² = 28190857 is a prime.

It is a Sophie Germain prime.

Together with 28190863, it forms a pair of twin primes.

It is a Chen prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28190863) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14095430 + 14095431.

It is an arithmetic number, because the mean of its divisors is an integer number (14095431).

Almost surely, 2^28190861 is an apocalyptic number.

It is an amenable number.

28190861 is a deficient number, since it is larger than the sum of its proper divisors (1).

28190861 is an equidigital number, since it uses as much as digits as its factorization.

28190861 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 6912, while the sum is 35.

The square root of 28190861 is about 5309.5066625818. The cubic root of 28190861 is about 304.3472954108.

The spelling of 28190861 in words is "twenty-eight million, one hundred ninety thousand, eight hundred sixty-one".