218428561 has 8 divisors (see below), whose sum is σ = 239218560. Its totient is φ = 198208272.

The previous prime is 218428547. The next prime is 218428571. The reversal of 218428561 is 165824812.

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

It is a cyclic number.

It is not a de Polignac number, because 218428561 - 2¹⁹ = 217904273 is a prime.

It is a super-2 number, since 2×218428561² = 95422072521061442, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 218428561.

It is not an unprimeable number, because it can be changed into a prime (218428531) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 141625 + ... + 143158.

It is an arithmetic number, because the mean of its divisors is an integer number (29902320).

Almost surely, 2^218428561 is an apocalyptic number.

It is an amenable number.

218428561 is a deficient number, since it is larger than the sum of its proper divisors (20789999).

218428561 is a wasteful number, since it uses less digits than its factorization.

218428561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 284855.

The product of its digits is 30720, while the sum is 37.

The square root of 218428561 is about 14779.3288413243. The cubic root of 218428561 is about 602.2402923321.

It can be divided in two parts, 21842 and 8561, that added together give a palindrome (30403).

The spelling of 218428561 in words is "two hundred eighteen million, four hundred twenty-eight thousand, five hundred sixty-one".