20181618 has 48 divisors (see below), whose sum is σ = 46829016. Its totient is φ = 6259200.

The previous prime is 20181583. The next prime is 20181619. The reversal of 20181618 is 81618102.

It can be written as a sum of positive squares in 4 ways, for example, as 20007729 + 173889 = 4473^2 + 417^2 .

It is a junction number, because it is equal to n+sod(n) for n = 20181591 and 20181600.

It is not an unprimeable number, because it can be changed into a prime (20181619) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 30580 + ... + 31232.

Almost surely, 2^20181618 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 20181618, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (23414508).

20181618 is an abundant number, since it is smaller than the sum of its proper divisors (26647398).

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

20181618 is a wasteful number, since it uses less digits than its factorization.

20181618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 779 (or 776 counting only the distinct ones).

The product of its (nonzero) digits is 768, while the sum is 27.

The square root of 20181618 is about 4492.3955747463. The cubic root of 20181618 is about 272.2609322032.

The spelling of 20181618 in words is "twenty million, one hundred eighty-one thousand, six hundred eighteen".