18728113 has 8 divisors (see below), whose sum is σ = 19423080. Its totient is φ = 18036480.

The previous prime is 18728111. The next prime is 18728117. The reversal of 18728113 is 31182781.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 10131489 + 8596624 = 3183^2 + 2932^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18728113 - 2¹ = 18728111 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18728111) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18681 + ... + 19657.

It is an arithmetic number, because the mean of its divisors is an integer number (2427885).

Almost surely, 2^18728113 is an apocalyptic number.

It is an amenable number.

18728113 is a deficient number, since it is larger than the sum of its proper divisors (694967).

18728113 is an equidigital number, since it uses as much as digits as its factorization.

18728113 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1667.

The product of its digits is 2688, while the sum is 31.

The square root of 18728113 is about 4327.5989878916. The cubic root of 18728113 is about 265.5612313451.

The spelling of 18728113 in words is "eighteen million, seven hundred twenty-eight thousand, one hundred thirteen".