7997221 has 4 divisors (see below), whose sum is σ = 8070700. Its totient is φ = 7923744.

The previous prime is 7997219. The next prime is 7997237. The reversal of 7997221 is 1227997.

It is the 1155-th star number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1227997 = 521 ⋅2357.

It can be written as a sum of positive squares in 2 ways, for example, as 1920996 + 6076225 = 1386^2 + 2465^2 .

It is a cyclic number.

It is not a de Polignac number, because 7997221 - 2¹ = 7997219 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 (7997201) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 36576 + ... + 36793.

It is an arithmetic number, because the mean of its divisors is an integer number (2017675).

Almost surely, 2^7997221 is an apocalyptic number.

It is an amenable number.

7997221 is a deficient number, since it is larger than the sum of its proper divisors (73479).

7997221 is a wasteful number, since it uses less digits than its factorization.

7997221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 73478.

The product of its digits is 15876, while the sum is 37.

The square root of 7997221 is about 2827.9358196395. The cubic root of 7997221 is about 199.9768389846.

The spelling of 7997221 in words is "seven million, nine hundred ninety-seven thousand, two hundred twenty-one".