671221 has 4 divisors (see below), whose sum is σ = 679392. Its totient is φ = 663052.

The previous prime is 671219. The next prime is 671233. The reversal of 671221 is 122176.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 671221 - 2¹ = 671219 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (671201) 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, 3961 + ... + 4126.

It is an arithmetic number, because the mean of its divisors is an integer number (169848).

2⁶⁷¹²²¹ is an apocalyptic number.

It is an amenable number.

671221 is a deficient number, since it is larger than the sum of its proper divisors (8171).

671221 is an equidigital number, since it uses as much as digits as its factorization.

671221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8170.

The product of its digits is 168, while the sum is 19.

The square root of 671221 is about 819.2807821498. The cubic root of 671221 is about 87.5565240225.

Adding to 671221 its reverse (122176), we get a palindrome (793397).

The spelling of 671221 in words is "six hundred seventy-one thousand, two hundred twenty-one".