989894981 has 2 divisors, whose sum is σ = 989894982. Its totient is φ = 989894980.

The previous prime is 989894947. The next prime is 989894987. The reversal of 989894981 is 189498989.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 539818756 + 450076225 = 23234^2 + 21215^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-989894981 is a prime.

It is a super-2 number, since 2×989894981² = 1959784146817980722, which contains 22 as substring.

It is a Sophie Germain prime.

It is an alternating number because its digits alternate between odd and even.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (989894987) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 494947490 + 494947491.

It is an arithmetic number, because the mean of its divisors is an integer number (494947491).

Almost surely, 2^989894981 is an apocalyptic number.

It is an amenable number.

989894981 is a deficient number, since it is larger than the sum of its proper divisors (1).

989894981 is an equidigital number, since it uses as much as digits as its factorization.

989894981 is an evil number, because the sum of its binary digits is even.

The product of its digits is 13436928, while the sum is 65.

The square root of 989894981 is about 31462.5965393831. The cubic root of 989894981 is about 996.6202504952.

The spelling of 989894981 in words is "nine hundred eighty-nine million, eight hundred ninety-four thousand, nine hundred eighty-one".