81523500809 has 8 divisors (see below), whose sum is σ = 82936617120. Its totient is φ = 80111430016.

The previous prime is 81523500739. The next prime is 81523500827. The reversal of 81523500809 is 90800532518.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81523500809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81523500869) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 103259 + ... + 416784.

It is an arithmetic number, because the mean of its divisors is an integer number (10367077140).

Almost surely, 2^81523500809 is an apocalyptic number.

It is an amenable number.

81523500809 is a deficient number, since it is larger than the sum of its proper divisors (1413116311).

81523500809 is a wasteful number, since it uses less digits than its factorization.

81523500809 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 522759.

The product of its (nonzero) digits is 86400, while the sum is 41.

The spelling of 81523500809 in words is "eighty-one billion, five hundred twenty-three million, five hundred thousand, eight hundred nine".