28398889 has 2 divisors, whose sum is σ = 28398890. Its totient is φ = 28398888.

The previous prime is 28398847. The next prime is 28398899. The reversal of 28398889 is 98889382.

28398889 is nontrivially palindromic in base 8.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 28355625 + 43264 = 5325^2 + 208^2 .

It is a cyclic number.

It is not a de Polignac number, because 28398889 - 2⁷ = 28398761 is a prime.

It is a super-3 number, since 3×28398889³ (a number of 23 digits) contains 333 as substring.

It is not a weakly prime, because it can be changed into another prime (28398809) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14199444 + 14199445.

It is an arithmetic number, because the mean of its divisors is an integer number (14199445).

Almost surely, 2^28398889 is an apocalyptic number.

It is an amenable number.

28398889 is a deficient number, since it is larger than the sum of its proper divisors (1).

28398889 is an equidigital number, since it uses as much as digits as its factorization.

28398889 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1990656, while the sum is 55.

The square root of 28398889 is about 5329.0607990527. The cubic root of 28398889 is about 305.0940818781.

The spelling of 28398889 in words is "twenty-eight million, three hundred ninety-eight thousand, eight hundred eighty-nine".