81641059018 has 8 divisors (see below), whose sum is σ = 122463995940. Its totient is φ = 40819727040.

The previous prime is 81641059013. The next prime is 81641059067. The reversal of 81641059018 is 81095014618.

It can be written as a sum of positive squares in 2 ways, for example, as 79285606929 + 2355452089 = 281577^2 + 48533^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (81641059013) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 264783 + ... + 483106.

Almost surely, 2^81641059018 is an apocalyptic number.

81641059018 is a deficient number, since it is larger than the sum of its proper divisors (40822936922).

81641059018 is a wasteful number, since it uses less digits than its factorization.

81641059018 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 802472.

The product of its (nonzero) digits is 69120, while the sum is 43.

The spelling of 81641059018 in words is "eighty-one billion, six hundred forty-one million, fifty-nine thousand, eighteen".