7131221 has 4 divisors (see below), whose sum is σ = 7140672. Its totient is φ = 7121772.

The previous prime is 7131217. The next prime is 7131259. The reversal of 7131221 is 1221317.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1221317 = 179 ⋅6823.

It is a cyclic number.

It is not a de Polignac number, because 7131221 - 2² = 7131217 is a prime.

It is a super-3 number, since 3×7131221³ (a number of 22 digits) contains 333 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 7131221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7131281) 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, 3485 + ... + 5138.

It is an arithmetic number, because the mean of its divisors is an integer number (1785168).

Almost surely, 2^7131221 is an apocalyptic number.

It is an amenable number.

7131221 is a deficient number, since it is larger than the sum of its proper divisors (9451).

7131221 is an equidigital number, since it uses as much as digits as its factorization.

7131221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9450.

The product of its digits is 84, while the sum is 17.

The square root of 7131221 is about 2670.4346088231. The cubic root of 7131221 is about 192.4810438409.

Adding to 7131221 its reverse (1221317), we get a palindrome (8352538).

The spelling of 7131221 in words is "seven million, one hundred thirty-one thousand, two hundred twenty-one".