28726921 has 2 divisors, whose sum is σ = 28726922. Its totient is φ = 28726920.

The previous prime is 28726909. The next prime is 28726927. The reversal of 28726921 is 12962782.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17598025 + 11128896 = 4195^2 + 3336^2 .

It is a cyclic number.

It is not a de Polignac number, because 28726921 - 2⁹ = 28726409 is a prime.

It is not a weakly prime, because it can be changed into another prime (28726927) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14363460 + 14363461.

It is an arithmetic number, because the mean of its divisors is an integer number (14363461).

Almost surely, 2^28726921 is an apocalyptic number.

It is an amenable number.

28726921 is a deficient number, since it is larger than the sum of its proper divisors (1).

28726921 is an equidigital number, since it uses as much as digits as its factorization.

28726921 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24192, while the sum is 37.

The square root of 28726921 is about 5359.7500874574. The cubic root of 28726921 is about 306.2642888793.

The spelling of 28726921 in words is "twenty-eight million, seven hundred twenty-six thousand, nine hundred twenty-one".