655221 has 16 divisors (see below), whose sum is σ = 1024128. Its totient is φ = 364800.

The previous prime is 655219. The next prime is 655223. The reversal of 655221 is 122556.

It is an interprime number because it is at equal distance from previous prime (655219) and next prime (655223).

It is not a de Polignac number, because 655221 - 2¹ = 655219 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a nialpdrome in base 10.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (655223) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 481 + ... + 1241.

It is an arithmetic number, because the mean of its divisors is an integer number (64008).

2⁶⁵⁵²²¹ is an apocalyptic number.

It is an amenable number.

655221 is a deficient number, since it is larger than the sum of its proper divisors (368907).

655221 is a wasteful number, since it uses less digits than its factorization.

655221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 812.

The product of its digits is 600, while the sum is 21.

The square root of 655221 is about 809.4572255530. The cubic root of 655221 is about 86.8552222804.

Adding to 655221 its reverse (122556), we get a palindrome (777777).

The spelling of 655221 in words is "six hundred fifty-five thousand, two hundred twenty-one".