81556934912 has 18 divisors (see below), whose sum is σ = 162795288558. Its totient is φ = 40778467328.

The previous prime is 81556934909. The next prime is 81556934923. The reversal of 81556934912 is 21943965518.

It can be written as a sum of positive squares in only one way, i.e., 81029038336 + 527896576 = 284656^2 + 22976^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 159290633 + ... + 159291144.

Almost surely, 2^81556934912 is an apocalyptic number.

It is an amenable number.

81556934912 is a deficient number, since it is larger than the sum of its proper divisors (81238353646).

81556934912 is an equidigital number, since it uses as much as digits as its factorization.

81556934912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 318581793 (or 318581779 counting only the distinct ones).

The product of its digits is 2332800, while the sum is 53.

The spelling of 81556934912 in words is "eighty-one billion, five hundred fifty-six million, nine hundred thirty-four thousand, nine hundred twelve".