181128989 has 2 divisors, whose sum is σ = 181128990. Its totient is φ = 181128988.

The previous prime is 181128977. The next prime is 181129009. The reversal of 181128989 is 989821181.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 140232964 + 40896025 = 11842^2 + 6395^2 .

It is a cyclic number.

It is not a de Polignac number, because 181128989 - 2⁸ = 181128733 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (181128089) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90564494 + 90564495.

It is an arithmetic number, because the mean of its divisors is an integer number (90564495).

Almost surely, 2^181128989 is an apocalyptic number.

It is an amenable number.

181128989 is a deficient number, since it is larger than the sum of its proper divisors (1).

181128989 is an equidigital number, since it uses as much as digits as its factorization.

181128989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 82944, while the sum is 47.

The square root of 181128989 is about 13458.4170317315. The cubic root of 181128989 is about 565.7996237855.

The spelling of 181128989 in words is "one hundred eighty-one million, one hundred twenty-eight thousand, nine hundred eighty-nine".