8221913891 has 4 divisors (see below), whose sum is σ = 8579388432. Its totient is φ = 7864439352.

The previous prime is 8221913873. The next prime is 8221913957. The reversal of 8221913891 is 1983191228.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 8221913891 - 2²⁶ = 8154805027 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8221913191) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 178737236 + ... + 178737281.

It is an arithmetic number, because the mean of its divisors is an integer number (2144847108).

Almost surely, 2^8221913891 is an apocalyptic number.

8221913891 is a deficient number, since it is larger than the sum of its proper divisors (357474541).

8221913891 is a wasteful number, since it uses less digits than its factorization.

8221913891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 357474540.

The product of its digits is 62208, while the sum is 44.

The square root of 8221913891 is about 90674.7698701243. The cubic root of 8221913891 is about 2018.3244193238.

The spelling of 8221913891 in words is "eight billion, two hundred twenty-one million, nine hundred thirteen thousand, eight hundred ninety-one".