8821991 has 2 divisors, whose sum is σ = 8821992. Its totient is φ = 8821990.

The previous prime is 8821979. The next prime is 8821999. The reversal of 8821991 is 1991288.

8821991 is nontrivially palindromic in base 6.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 8821991 - 2⁶ = 8821927 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8821999) 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 as a sum of consecutive naturals, namely, 4410995 + 4410996.

It is an arithmetic number, because the mean of its divisors is an integer number (4410996).

Almost surely, 2^8821991 is an apocalyptic number.

8821991 is a deficient number, since it is larger than the sum of its proper divisors (1).

8821991 is an equidigital number, since it uses as much as digits as its factorization.

8821991 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 10368, while the sum is 38.

The square root of 8821991 is about 2970.1836643548. The cubic root of 8821991 is about 206.6278563380.

The spelling of 8821991 in words is "eight million, eight hundred twenty-one thousand, nine hundred ninety-one".