7891221 has 8 divisors (see below), whose sum is σ = 11331040. Its totient is φ = 4856112.

The previous prime is 7891217. The next prime is 7891237. The reversal of 7891221 is 1221987.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 7891221 - 2² = 7891217 is a prime.

It is a Duffinian number.

7891221 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7891211) 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 7 ways as a sum of consecutive naturals, for example, 101131 + ... + 101208.

It is an arithmetic number, because the mean of its divisors is an integer number (1416380).

Almost surely, 2^7891221 is an apocalyptic number.

It is an amenable number.

7891221 is a deficient number, since it is larger than the sum of its proper divisors (3439819).

7891221 is a wasteful number, since it uses less digits than its factorization.

7891221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 202355.

The product of its digits is 2016, while the sum is 30.

The square root of 7891221 is about 2809.1317163850. The cubic root of 7891221 is about 199.0893683764.

It can be divided in two parts, 789 and 1221, that multiplied together give a palindrome (963369).

The spelling of 7891221 in words is "seven million, eight hundred ninety-one thousand, two hundred twenty-one".