81066047842 has 16 divisors (see below), whose sum is σ = 134492114232. Its totient is φ = 36403879680.

The previous prime is 81066047801. The next prime is 81066047851. The reversal of 81066047842 is 24874066018.

It is a Cunningham number, because it is equal to 284721²+1.

It can be written as a sum of positive squares in 4 ways, for example, as 81066047841 + 1 = 284721^2 + 1^2 .

It is a super-2 number, since 2×81066047842² (a number of 23 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 81066047792 and 81066047801.

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, 42133159 + ... + 42135082.

Almost surely, 2^81066047842 is an apocalyptic number.

81066047842 is a deficient number, since it is larger than the sum of its proper divisors (53426066390).

81066047842 is a wasteful number, since it uses less digits than its factorization.

81066047842 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 84268293.

The product of its (nonzero) digits is 516096, while the sum is 46.

The spelling of 81066047842 in words is "eighty-one billion, sixty-six million, forty-seven thousand, eight hundred forty-two".