989181981 has 12 divisors (see below), whose sum is σ = 1442966460. Its totient is φ = 652924800.

The previous prime is 989181979. The next prime is 989181997. The reversal of 989181981 is 189181989.

It can be written as a sum of positive squares in 2 ways, for example, as 847333881 + 141848100 = 29109^2 + 11910^2 .

It is not a de Polignac number, because 989181981 - 2¹ = 989181979 is a prime.

It is a super-2 number, since 2×989181981² = 1956961983070168722, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (989181931) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 543196 + ... + 545013.

It is an arithmetic number, because the mean of its divisors is an integer number (120247205).

Almost surely, 2^989181981 is an apocalyptic number.

It is an amenable number.

989181981 is a deficient number, since it is larger than the sum of its proper divisors (453784479).

989181981 is a wasteful number, since it uses less digits than its factorization.

989181981 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1088316 (or 1088313 counting only the distinct ones).

The product of its digits is 373248, while the sum is 54.

The square root of 989181981 is about 31451.2635835192. The cubic root of 989181981 is about 996.3809116670.

The spelling of 989181981 in words is "nine hundred eighty-nine million, one hundred eighty-one thousand, nine hundred eighty-one".