81168441856 has 20 divisors (see below), whose sum is σ = 162178352622. Its totient is φ = 40584220672.

The previous prime is 81168441829. The next prime is 81168441857. The reversal of 81168441856 is 65814486118.

It can be written as a sum of positive squares in only one way, i.e., 48392960256 + 32775481600 = 219984^2 + 181040^2 .

It is not an unprimeable number, because it can be changed into a prime (81168441857) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 79265545 + ... + 79266568.

Almost surely, 2^81168441856 is an apocalyptic number.

It is an amenable number.

81168441856 is a deficient number, since it is larger than the sum of its proper divisors (81009910766).

81168441856 is an equidigital number, since it uses as much as digits as its factorization.

81168441856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158532131 (or 158532115 counting only the distinct ones).

The product of its digits is 1474560, while the sum is 52.

The spelling of 81168441856 in words is "eighty-one billion, one hundred sixty-eight million, four hundred forty-one thousand, eight hundred fifty-six".