731221 has 4 divisors (see below), whose sum is σ = 774252. Its totient is φ = 688192.

The previous prime is 731219. The next prime is 731233. The reversal of 731221 is 122137.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 122137 = 37 ⋅3301.

It can be written as a sum of positive squares in 2 ways, for example, as 579121 + 152100 = 761^2 + 390^2 .

It is a cyclic number.

It is not a de Polignac number, because 731221 - 2¹ = 731219 is a prime.

It is a Duffinian number.

731221 is a lucky number.

It is a junction number, because it is equal to n+sod(n) for n = 731195 and 731204.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (731201) 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, 21490 + ... + 21523.

It is an arithmetic number, because the mean of its divisors is an integer number (193563).

2⁷³¹²²¹ is an apocalyptic number.

It is an amenable number.

731221 is a deficient number, since it is larger than the sum of its proper divisors (43031).

731221 is a wasteful number, since it uses less digits than its factorization.

731221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 43030.

The product of its digits is 84, while the sum is 16.

The square root of 731221 is about 855.1146122012. The cubic root of 731221 is about 90.0913065136.

Subtracting from 731221 its product of digits (84), we obtain a palindrome (731137).

Adding to 731221 its reverse (122137), we get a palindrome (853358).

The spelling of 731221 in words is "seven hundred thirty-one thousand, two hundred twenty-one".