28031389 has 2 divisors, whose sum is σ = 28031390. Its totient is φ = 28031388.

The previous prime is 28031369. The next prime is 28031401. The reversal of 28031389 is 98313082.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21930489 + 6100900 = 4683^2 + 2470^2 .

It is a cyclic number.

It is not a de Polignac number, because 28031389 - 2⁷ = 28031261 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (28031309) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14015694 + 14015695.

It is an arithmetic number, because the mean of its divisors is an integer number (14015695).

Almost surely, 2^28031389 is an apocalyptic number.

It is an amenable number.

28031389 is a deficient number, since it is larger than the sum of its proper divisors (1).

28031389 is an equidigital number, since it uses as much as digits as its factorization.

28031389 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10368, while the sum is 34.

The square root of 28031389 is about 5294.4677730627. The cubic root of 28031389 is about 303.7723256352.

The spelling of 28031389 in words is "twenty-eight million, thirty-one thousand, three hundred eighty-nine".