7909171221 has 16 divisors (see below), whose sum is σ = 12112640000. Its totient is φ = 4496812848.

The previous prime is 7909171217. The next prime is 7909171229. The reversal of 7909171221 is 1221719097.

It is not a de Polignac number, because 7909171221 - 2² = 7909171217 is a prime.

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 7909171221.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7909171229) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 942121 + ... + 950478.

It is an arithmetic number, because the mean of its divisors is an integer number (757040000).

Almost surely, 2^7909171221 is an apocalyptic number.

It is an amenable number.

7909171221 is a deficient number, since it is larger than the sum of its proper divisors (4203468779).

7909171221 is a wasteful number, since it uses less digits than its factorization.

7909171221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1892808.

The product of its (nonzero) digits is 15876, while the sum is 39.

The square root of 7909171221 is about 88933.5213572475. The cubic root of 7909171221 is about 1992.4021076502.

The spelling of 7909171221 in words is "seven billion, nine hundred nine million, one hundred seventy-one thousand, two hundred twenty-one".