81387609 has 8 divisors (see below), whose sum is σ = 110356320. Its totient is φ = 53338656.

The previous prime is 81387577. The next prime is 81387611. The reversal of 81387609 is 90678318.

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

It is not a de Polignac number, because 81387609 - 2⁵ = 81387577 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81387629) 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 7 ways as a sum of consecutive naturals, for example, 229732 + ... + 230085.

It is an arithmetic number, because the mean of its divisors is an integer number (13794540).

Almost surely, 2^81387609 is an apocalyptic number.

It is an amenable number.

81387609 is a deficient number, since it is larger than the sum of its proper divisors (28968711).

81387609 is a wasteful number, since it uses less digits than its factorization.

81387609 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 459879.

The product of its (nonzero) digits is 72576, while the sum is 42.

The square root of 81387609 is about 9021.5081333444. The cubic root of 81387609 is about 433.3639322903.

The spelling of 81387609 in words is "eighty-one million, three hundred eighty-seven thousand, six hundred nine".