28993813 has 4 divisors (see below), whose sum is σ = 29047948. Its totient is φ = 28939680.

The previous prime is 28993799. The next prime is 28993841. The reversal of 28993813 is 31839982.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12404484 + 16589329 = 3522^2 + 4073^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-28993813 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 28993813.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28993843) 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 in 3 ways as a sum of consecutive naturals, for example, 26256 + ... + 27337.

It is an arithmetic number, because the mean of its divisors is an integer number (7261987).

Almost surely, 2^28993813 is an apocalyptic number.

It is an amenable number.

28993813 is a deficient number, since it is larger than the sum of its proper divisors (54135).

28993813 is an equidigital number, since it uses as much as digits as its factorization.

28993813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 54134.

The product of its digits is 93312, while the sum is 43.

The square root of 28993813 is about 5384.5903279637. The cubic root of 28993813 is about 307.2098322512.

The spelling of 28993813 in words is "twenty-eight million, nine hundred ninety-three thousand, eight hundred thirteen".