989818891 has 2 divisors, whose sum is σ = 989818892. Its totient is φ = 989818890.

The previous prime is 989818883. The next prime is 989818909. The reversal of 989818891 is 198818989.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 989818891 - 2³ = 989818883 is a prime.

It is not a weakly prime, because it can be changed into another prime (989518891) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 494909445 + 494909446.

It is an arithmetic number, because the mean of its divisors is an integer number (494909446).

Almost surely, 2^989818891 is an apocalyptic number.

989818891 is a deficient number, since it is larger than the sum of its proper divisors (1).

989818891 is an equidigital number, since it uses as much as digits as its factorization.

989818891 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2985984, while the sum is 61.

The square root of 989818891 is about 31461.3873025332. The cubic root of 989818891 is about 996.5947141911.

The spelling of 989818891 in words is "nine hundred eighty-nine million, eight hundred eighteen thousand, eight hundred ninety-one".