81432865 has 8 divisors (see below), whose sum is σ = 99321768. Its totient is φ = 64078080.

The previous prime is 81432863. The next prime is 81432881. The reversal of 81432865 is 56823418.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 289 + 81432576 = 17^2 + 9024^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 81432865 - 2¹ = 81432863 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81432863) 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 7 ways as a sum of consecutive naturals, for example, 133192 + ... + 133801.

It is an arithmetic number, because the mean of its divisors is an integer number (12415221).

Almost surely, 2^81432865 is an apocalyptic number.

It is an amenable number.

81432865 is a deficient number, since it is larger than the sum of its proper divisors (17888903).

81432865 is a wasteful number, since it uses less digits than its factorization.

81432865 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 267059.

The product of its digits is 46080, while the sum is 37.

The square root of 81432865 is about 9024.0160128404. The cubic root of 81432865 is about 433.4442421569. Note that the first 3 decimals are identical.

The spelling of 81432865 in words is "eighty-one million, four hundred thirty-two thousand, eight hundred sixty-five".