7221312 has 140 divisors (see below), whose sum is σ = 24587200. Its totient is φ = 2052864.

The previous prime is 7221307. The next prime is 7221353. The reversal of 7221312 is 2131227.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nude number because it is divisible by every one of its digits and also a Zuckerman number because it is divisible by the product of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 36189 + ... + 36387.

Almost surely, 2^7221312 is an apocalyptic number.

7221312 is a gapful number since it is divisible by the number (72) formed by its first and last digit.

7221312 is the 1344-th decagonal number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 7221312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (12293600).

7221312 is an abundant number, since it is smaller than the sum of its proper divisors (17365888).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

7221312 is a wasteful number, since it uses less digits than its factorization.

7221312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 230 (or 211 counting only the distinct ones).

The product of its digits is 168, while the sum is 18.

The square root of 7221312 is about 2687.2498953391. The cubic root of 7221312 is about 193.2882124853.

Adding to 7221312 its reverse (2131227), we get a palindrome (9352539).

The spelling of 7221312 in words is "seven million, two hundred twenty-one thousand, three hundred twelve".