81169289 has 4 divisors (see below), whose sum is σ = 83968260. Its totient is φ = 78370320.

The previous prime is 81169267. The next prime is 81169307. The reversal of 81169289 is 98296118.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 29214025 + 51955264 = 5405^2 + 7208^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81169289 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81169489) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1399442 + ... + 1399499.

It is an arithmetic number, because the mean of its divisors is an integer number (20992065).

Almost surely, 2^81169289 is an apocalyptic number.

It is an amenable number.

81169289 is a deficient number, since it is larger than the sum of its proper divisors (2798971).

81169289 is a wasteful number, since it uses less digits than its factorization.

81169289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2798970.

The product of its digits is 62208, while the sum is 44.

The square root of 81169289 is about 9009.4000355185. The cubic root of 81169289 is about 432.9760897215.

The spelling of 81169289 in words is "eighty-one million, one hundred sixty-nine thousand, two hundred eighty-nine".