18128881 has 4 divisors (see below), whose sum is σ = 18152100. Its totient is φ = 18105664.

The previous prime is 18128879. The next prime is 18128897. The reversal of 18128881 is 18882181.

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 13359025 + 4769856 = 3655^2 + 2184^2 .

It is a cyclic number.

It is not a de Polignac number, because 18128881 - 2¹ = 18128879 is a prime.

It is a super-2 number, since 2×18128881² = 657312652624322, which contains 22 as substring.

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 18128881.

It is not an unprimeable number, because it can be changed into a prime (18128801) 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, 10396 + ... + 12013.

It is an arithmetic number, because the mean of its divisors is an integer number (4538025).

Almost surely, 2^18128881 is an apocalyptic number.

It is an amenable number.

18128881 is a deficient number, since it is larger than the sum of its proper divisors (23219).

18128881 is an equidigital number, since it uses as much as digits as its factorization.

18128881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23218.

The product of its digits is 8192, while the sum is 37.

The square root of 18128881 is about 4257.8023674191. The cubic root of 18128881 is about 262.6981409529.

The spelling of 18128881 in words is "eighteen million, one hundred twenty-eight thousand, eight hundred eighty-one".