989555981 has 2 divisors, whose sum is σ = 989555982. Its totient is φ = 989555980.

The previous prime is 989555977. The next prime is 989555989. The reversal of 989555981 is 189555989.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 980253481 + 9302500 = 31309^2 + 3050^2 .

It is a cyclic number.

It is not a de Polignac number, because 989555981 - 2² = 989555977 is a prime.

It is a super-4 number, since 4×989555981⁴ (a number of 37 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 989555981.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (989555989) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 494777990 + 494777991.

It is an arithmetic number, because the mean of its divisors is an integer number (494777991).

Almost surely, 2^989555981 is an apocalyptic number.

It is an amenable number.

989555981 is a deficient number, since it is larger than the sum of its proper divisors (1).

989555981 is an equidigital number, since it uses as much as digits as its factorization.

989555981 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 5832000, while the sum is 59.

The square root of 989555981 is about 31457.2087286841. The cubic root of 989555981 is about 996.5064697926.

The spelling of 989555981 in words is "nine hundred eighty-nine million, five hundred fifty-five thousand, nine hundred eighty-one".