81161086724 has 24 divisors (see below), whose sum is σ = 150512088888. Its totient is φ = 38161612800.

The previous prime is 81161086709. The next prime is 81161086733. The reversal of 81161086724 is 42768016118.

It can be written as a sum of positive squares in 4 ways, for example, as 16806529600 + 64354557124 = 129640^2 + 253682^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 415229 + ... + 578564.

It is an arithmetic number, because the mean of its divisors is an integer number (6271337037).

Almost surely, 2^81161086724 is an apocalyptic number.

It is an amenable number.

81161086724 is a deficient number, since it is larger than the sum of its proper divisors (69351002164).

81161086724 is a wasteful number, since it uses less digits than its factorization.

81161086724 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 995015 (or 995013 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 44.

The spelling of 81161086724 in words is "eighty-one billion, one hundred sixty-one million, eighty-six thousand, seven hundred twenty-four".