81811027568 has 20 divisors (see below), whose sum is σ = 158523110568. Its totient is φ = 40901837760.

The previous prime is 81811027547. The next prime is 81811027643. The reversal of 81811027568 is 86572011818.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 41471 + ... + 406622.

Almost surely, 2^81811027568 is an apocalyptic number.

It is an amenable number.

81811027568 is a deficient number, since it is larger than the sum of its proper divisors (76712083000).

81811027568 is a wasteful number, since it uses less digits than its factorization.

81811027568 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 459512 (or 459506 counting only the distinct ones).

The product of its (nonzero) digits is 215040, while the sum is 47.

The spelling of 81811027568 in words is "eighty-one billion, eight hundred eleven million, twenty-seven thousand, five hundred sixty-eight".