618221 has 4 divisors (see below), whose sum is σ = 624444. Its totient is φ = 612000.

The previous prime is 618199. The next prime is 618227. The reversal of 618221 is 122816.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 354025 + 264196 = 595^2 + 514^2 .

It is a cyclic number.

It is not a de Polignac number, because 618221 - 2¹⁸ = 356077 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 618193 and 618202.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (618227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2960 + ... + 3161.

It is an arithmetic number, because the mean of its divisors is an integer number (156111).

2⁶¹⁸²²¹ is an apocalyptic number.

It is an amenable number.

618221 is a deficient number, since it is larger than the sum of its proper divisors (6223).

618221 is a wasteful number, since it uses less digits than its factorization.

618221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6222.

The product of its digits is 192, while the sum is 20.

The square root of 618221 is about 786.2703097536. The cubic root of 618221 is about 85.1885548925.

The spelling of 618221 in words is "six hundred eighteen thousand, two hundred twenty-one".