18681228 has 36 divisors (see below), whose sum is σ = 48117888. Its totient is φ = 6108960.

The previous prime is 18681227. The next prime is 18681239. The reversal of 18681228 is 82218681.

It is a tau number, because it is divible by the number of its divisors (36).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 18681192 and 18681201.

It is not an unprimeable number, because it can be changed into a prime (18681227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2988 + ... + 6803.

It is an arithmetic number, because the mean of its divisors is an integer number (1336608).

Almost surely, 2^18681228 is an apocalyptic number.

18681228 is a gapful number since it is divisible by the number (18) formed by its first and last digit.

It is an amenable number.

18681228 is an abundant number, since it is smaller than the sum of its proper divisors (29436660).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18681228 is a wasteful number, since it uses less digits than its factorization.

18681228 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9854 (or 9849 counting only the distinct ones).

The product of its digits is 12288, while the sum is 36.

The square root of 18681228 is about 4322.1786173179. The cubic root of 18681228 is about 265.3394392395.

The spelling of 18681228 in words is "eighteen million, six hundred eighty-one thousand, two hundred twenty-eight".