81143969 has 4 divisors (see below), whose sum is σ = 82474260. Its totient is φ = 79813680.

The previous prime is 81143963. The next prime is 81143971. The reversal of 81143969 is 96934118.

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 21669025 + 59474944 = 4655^2 + 7712^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81143969 is a prime.

It is a super-2 number, since 2×81143969² = 13168687410145922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81143963) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 665054 + ... + 665175.

It is an arithmetic number, because the mean of its divisors is an integer number (20618565).

Almost surely, 2^81143969 is an apocalyptic number.

It is an amenable number.

81143969 is a deficient number, since it is larger than the sum of its proper divisors (1330291).

81143969 is a wasteful number, since it uses less digits than its factorization.

81143969 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1330290.

The product of its digits is 46656, while the sum is 41.

The square root of 81143969 is about 9007.9947269079. The cubic root of 81143969 is about 432.9310640931.

The spelling of 81143969 in words is "eighty-one million, one hundred forty-three thousand, nine hundred sixty-nine".