8891921 has 2 divisors, whose sum is σ = 8891922. Its totient is φ = 8891920.

The previous prime is 8891899. The next prime is 8891923. The reversal of 8891921 is 1291988.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 8761600 + 130321 = 2960^2 + 361^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-8891921 is a prime.

Together with 8891923, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (8891923) 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 as a sum of consecutive naturals, namely, 4445960 + 4445961.

It is an arithmetic number, because the mean of its divisors is an integer number (4445961).

Almost surely, 2^8891921 is an apocalyptic number.

It is an amenable number.

8891921 is a deficient number, since it is larger than the sum of its proper divisors (1).

8891921 is an equidigital number, since it uses as much as digits as its factorization.

8891921 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 8891921 is about 2981.9324271351. The cubic root of 8891921 is about 207.1723847381.

The spelling of 8891921 in words is "eight million, eight hundred ninety-one thousand, nine hundred twenty-one".