28978993 has 2 divisors, whose sum is σ = 28978994. Its totient is φ = 28978992.

The previous prime is 28978991. The next prime is 28979051. The reversal of 28978993 is 39987982.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 28976689 + 2304 = 5383^2 + 48^2 .

It is a cyclic number.

It is not a de Polignac number, because 28978993 - 2¹ = 28978991 is a prime.

Together with 28978991, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (28978991) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 14489496 + 14489497.

It is an arithmetic number, because the mean of its divisors is an integer number (14489497).

Almost surely, 2^28978993 is an apocalyptic number.

It is an amenable number.

28978993 is a deficient number, since it is larger than the sum of its proper divisors (1).

28978993 is an equidigital number, since it uses as much as digits as its factorization.

28978993 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1959552, while the sum is 55.

The square root of 28978993 is about 5383.2140028054. The cubic root of 28978993 is about 307.1574805575.

The spelling of 28978993 in words is "twenty-eight million, nine hundred seventy-eight thousand, nine hundred ninety-three".