6723221 has 4 divisors (see below), whose sum is σ = 6887244. Its totient is φ = 6559200.

The previous prime is 6723217. The next prime is 6723251. The reversal of 6723221 is 1223276.

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 2292196 + 4431025 = 1514^2 + 2105^2 .

It is a cyclic number.

It is not a de Polignac number, because 6723221 - 2² = 6723217 is a prime.

It is a super-2 number, since 2×6723221² = 90403401229682, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6723251) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 81950 + ... + 82031.

It is an arithmetic number, because the mean of its divisors is an integer number (1721811).

Almost surely, 2^6723221 is an apocalyptic number.

It is an amenable number.

6723221 is a deficient number, since it is larger than the sum of its proper divisors (164023).

6723221 is a wasteful number, since it uses less digits than its factorization.

6723221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 164022.

The product of its digits is 1008, while the sum is 23.

The square root of 6723221 is about 2592.9174687984. The cubic root of 6723221 is about 188.7379045799.

Adding to 6723221 its reverse (1223276), we get a palindrome (7946497).

Subtracting from 6723221 its reverse (1223276), we obtain a palindrome (5499945).

The spelling of 6723221 in words is "six million, seven hundred twenty-three thousand, two hundred twenty-one".