18278220 has 72 divisors (see below), whose sum is σ = 53050032. Its totient is φ = 4702080.

The previous prime is 18278201. The next prime is 18278231. The reversal of 18278220 is 2287281.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 57502 + ... + 57818.

It is an arithmetic number, because the mean of its divisors is an integer number (736806).

Almost surely, 2^18278220 is an apocalyptic number.

18278220 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 18278220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (26525016).

18278220 is an abundant number, since it is smaller than the sum of its proper divisors (34771812).

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

18278220 is a wasteful number, since it uses less digits than its factorization.

18278220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 391 (or 358 counting only the distinct ones).

The product of its (nonzero) digits is 3584, while the sum is 30.

The square root of 18278220 is about 4275.3034979987. The cubic root of 18278220 is about 263.4175058948.

It can be divided in two parts, 1827 and 8220, that multiplied together give a triangular number (15017940 = T₅₄₈₀).

The spelling of 18278220 in words is "eighteen million, two hundred seventy-eight thousand, two hundred twenty".