218691018 has 72 divisors (see below), whose sum is σ = 593621028. Its totient is φ = 57673728.

The previous prime is 218691013. The next prime is 218691037. The reversal of 218691018 is 810196812.

218691018 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 162486009 + 56205009 = 12747^2 + 7497^2 .

It is a super-2 number, since 2×218691018² = 95651522707752648, which contains 22 as substring.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (218691013) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1930 + ... + 21002.

Almost surely, 2^218691018 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 218691018, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (296810514).

218691018 is an abundant number, since it is smaller than the sum of its proper divisors (374930010).

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

218691018 is a wasteful number, since it uses less digits than its factorization.

218691018 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19108 (or 19098 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 36.

The square root of 218691018 is about 14788.2053677923. The cubic root of 218691018 is about 602.4814068859.

The spelling of 218691018 in words is "two hundred eighteen million, six hundred ninety-one thousand, eighteen".