221716618 has 8 divisors (see below), whose sum is σ = 352138212. Its totient is φ = 104337216.

The previous prime is 221716613. The next prime is 221716637. The reversal of 221716618 is 816617122.

It can be written as a sum of positive squares in 2 ways, for example, as 220136569 + 1580049 = 14837^2 + 1257^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-3 number, since 3×221716618³ (a number of 26 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (34), and also a Moran number because the ratio is a prime number: 6521077 = 221716618 / (2 + 2 + 1 + 7 + 1 + 6 + 6 + 1 + 8).

It is not an unprimeable number, because it can be changed into a prime (221716613) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3260505 + ... + 3260572.

Almost surely, 2^221716618 is an apocalyptic number.

221716618 is a deficient number, since it is larger than the sum of its proper divisors (130421594).

221716618 is a wasteful number, since it uses less digits than its factorization.

221716618 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6521096.

The product of its digits is 8064, while the sum is 34.

The square root of 221716618 is about 14890.1517117859. The cubic root of 221716618 is about 605.2471435238.

The spelling of 221716618 in words is "two hundred twenty-one million, seven hundred sixteen thousand, six hundred eighteen".