81359876840842 has 16 divisors (see below), whose sum is σ = 122547068876232. Its totient is φ = 40510856263680.

The previous prime is 81359876840839. The next prime is 81359876840849. The reversal of 81359876840842 is 24804867895318.

It is a Cunningham number, because it is equal to 9019971²+1.

It can be written as a sum of positive squares in 4 ways, for example, as 61188361645401 + 20171515195441 = 7822299^2 + 4491271^2 .

It is not an unprimeable number, because it can be changed into a prime (81359876840849) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 78782248 + ... + 79808284.

It is a 1-persistent number, because it is pandigital, but 2⋅81359876840842 = 162719753681684 is not.

Almost surely, 2^{81359876840842} is an apocalyptic number.

81359876840842 is a deficient number, since it is larger than the sum of its proper divisors (41187192035390).

81359876840842 is a wasteful number, since it uses less digits than its factorization.

81359876840842 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1190793.

The product of its (nonzero) digits is 743178240, while the sum is 73.

The spelling of 81359876840842 in words is "eighty-one trillion, three hundred fifty-nine billion, eight hundred seventy-six million, eight hundred forty thousand, eight hundred forty-two".