81635866568 has 16 divisors (see below), whose sum is σ = 154497786480. Its totient is φ = 40436456848.

The previous prime is 81635866567. The next prime is 81635866579. The reversal of 81635866568 is 86566853618.

It is a self number, because there is not a number n which added to its sum of digits gives 81635866568.

It is not an unprimeable number, because it can be changed into a prime (81635866567) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 47683646 + ... + 47685357.

It is an arithmetic number, because the mean of its divisors is an integer number (9656111655).

Almost surely, 2^81635866568 is an apocalyptic number.

It is an amenable number.

81635866568 is a deficient number, since it is larger than the sum of its proper divisors (72861919912).

81635866568 is a wasteful number, since it uses less digits than its factorization.

81635866568 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 95369116 (or 95369112 counting only the distinct ones).

The product of its digits is 49766400, while the sum is 62.

The spelling of 81635866568 in words is "eighty-one billion, six hundred thirty-five million, eight hundred sixty-six thousand, five hundred sixty-eight".