28381813 has 4 divisors (see below), whose sum is σ = 28416960. Its totient is φ = 28346668.

The previous prime is 28381811. The next prime is 28381819. The reversal of 28381813 is 31818382.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 28381813 - 2¹ = 28381811 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28381811) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16333 + ... + 17986.

It is an arithmetic number, because the mean of its divisors is an integer number (7104240).

Almost surely, 2^28381813 is an apocalyptic number.

It is an amenable number.

28381813 is a deficient number, since it is larger than the sum of its proper divisors (35147).

28381813 is an equidigital number, since it uses as much as digits as its factorization.

28381813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35146.

The product of its digits is 9216, while the sum is 34.

The square root of 28381813 is about 5327.4583996499. The cubic root of 28381813 is about 305.0329194961.

The spelling of 28381813 in words is "twenty-eight million, three hundred eighty-one thousand, eight hundred thirteen".