18665645220 has 144 divisors (see below), whose sum is σ = 59980415040. Its totient is φ = 4685361408.

The previous prime is 18665645191. The next prime is 18665645233. The reversal of 18665645220 is 2254656681.

18665645220 is a `hidden beast` number, since 1 + 8 + 6 + 65 + 64 + 522 + 0 = 666.

It is a super-2 number, since 2×18665645220² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 519559 + ... + 554321.

It is an arithmetic number, because the mean of its divisors is an integer number (416530660).

Almost surely, 2^18665645220 is an apocalyptic number.

18665645220 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 18665645220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29990207520).

18665645220 is an abundant number, since it is smaller than the sum of its proper divisors (41314769820).

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

18665645220 is a wasteful number, since it uses less digits than its factorization.

18665645220 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34954 (or 34949 counting only the distinct ones).

The product of its (nonzero) digits is 691200, while the sum is 45.

The spelling of 18665645220 in words is "eighteen billion, six hundred sixty-five million, six hundred forty-five thousand, two hundred twenty".