7917221 has 8 divisors (see below), whose sum is σ = 8897280. Its totient is φ = 6990192.

The previous prime is 7917211. The next prime is 7917229. The reversal of 7917221 is 1227197.

7917221 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

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

It is a cyclic number.

It is not a de Polignac number, because 7917221 - 2¹⁰ = 7916197 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7917229) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 12941 + ... + 13538.

It is an arithmetic number, because the mean of its divisors is an integer number (1112160).

Almost surely, 2^7917221 is an apocalyptic number.

It is an amenable number.

7917221 is a deficient number, since it is larger than the sum of its proper divisors (980059).

7917221 is a wasteful number, since it uses less digits than its factorization.

7917221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 26515.

The product of its digits is 1764, while the sum is 29.

The square root of 7917221 is about 2813.7556752497. The cubic root of 7917221 is about 199.3077819348.

The spelling of 7917221 in words is "seven million, nine hundred seventeen thousand, two hundred twenty-one".