28639993 has 2 divisors, whose sum is σ = 28639994. Its totient is φ = 28639992.

The previous prime is 28639979. The next prime is 28640033. The reversal of 28639993 is 39993682.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 27741289 + 898704 = 5267^2 + 948^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28639993 is a prime.

It is not a weakly prime, because it can be changed into another prime (28639913) 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, 14319996 + 14319997.

It is an arithmetic number, because the mean of its divisors is an integer number (14319997).

Almost surely, 2^28639993 is an apocalyptic number.

It is an amenable number.

28639993 is a deficient number, since it is larger than the sum of its proper divisors (1).

28639993 is an equidigital number, since it uses as much as digits as its factorization.

28639993 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 629856, while the sum is 49.

The square root of 28639993 is about 5351.6346100981. The cubic root of 28639993 is about 305.9550569790.

The spelling of 28639993 in words is "twenty-eight million, six hundred thirty-nine thousand, nine hundred ninety-three".