891322021 has 2 divisors, whose sum is σ = 891322022. Its totient is φ = 891322020.

The previous prime is 891322009. The next prime is 891322031. The reversal of 891322021 is 120223198.

891322021 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 497736100 + 393585921 = 22310^2 + 19839^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-891322021 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (891322031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 445661010 + 445661011.

It is an arithmetic number, because the mean of its divisors is an integer number (445661011).

Almost surely, 2^891322021 is an apocalyptic number.

It is an amenable number.

891322021 is a deficient number, since it is larger than the sum of its proper divisors (1).

891322021 is an equidigital number, since it uses as much as digits as its factorization.

891322021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 891322021 is about 29855.0166806184. The cubic root of 891322021 is about 962.3762102224.

The spelling of 891322021 in words is "eight hundred ninety-one million, three hundred twenty-two thousand, twenty-one".