642218 has 4 divisors (see below), whose sum is σ = 963330. Its totient is φ = 321108.

The previous prime is 642217. The next prime is 642223. The reversal of 642218 is 812246.

642218 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 812246 = 2 ⋅406123.

It can be written as a sum of positive squares in only one way, i.e., 573049 + 69169 = 757^2 + 263^2 .

It is a junction number, because it is equal to n+sod(n) for n = 642193 and 642202.

It is not an unprimeable number, because it can be changed into a prime (642211) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 160553 + ... + 160556.

2⁶⁴²²¹⁸ is an apocalyptic number.

642218 is a deficient number, since it is larger than the sum of its proper divisors (321112).

642218 is a wasteful number, since it uses less digits than its factorization.

642218 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 321111.

The product of its digits is 768, while the sum is 23.

The square root of 642218 is about 801.3850510210. The cubic root of 642218 is about 86.2768256542.

It can be divided in two parts, 6 and 42218, that added together give a palindrome (42224).

The spelling of 642218 in words is "six hundred forty-two thousand, two hundred eighteen".