81552687997 has 24 divisors (see below), whose sum is σ = 95438351736. Its totient is φ = 69391872000.

The previous prime is 81552687919. The next prime is 81552688013. The reversal of 81552687997 is 79978625518.

It can be written as a sum of positive squares in 4 ways, for example, as 2092971001 + 79459716996 = 45749^2 + 281886^2 .

It is a de Polignac number, because none of the positive numbers 2^k-81552687997 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81552687397) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 262797 + ... + 481837.

It is an arithmetic number, because the mean of its divisors is an integer number (3976597989).

Almost surely, 2^81552687997 is an apocalyptic number.

It is an amenable number.

81552687997 is a deficient number, since it is larger than the sum of its proper divisors (13885663739).

81552687997 is a wasteful number, since it uses less digits than its factorization.

81552687997 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 219261 (or 219250 counting only the distinct ones).

The product of its digits is 76204800, while the sum is 67.

The spelling of 81552687997 in words is "eighty-one billion, five hundred fifty-two million, six hundred eighty-seven thousand, nine hundred ninety-seven".