81539188104 has 128 divisors (see below), whose sum is σ = 235312128000. Its totient is φ = 23285548800.

The previous prime is 81539188079. The next prime is 81539188153. The reversal of 81539188104 is 40188193518.

It is a happy number.

It is a super-2 number, since 2×81539188104² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 915502 + ... + 1000610.

It is an arithmetic number, because the mean of its divisors is an integer number (1838376000).

Almost surely, 2^81539188104 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81539188104, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (117656064000).

81539188104 is an abundant number, since it is smaller than the sum of its proper divisors (153772939896).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81539188104 is a wasteful number, since it uses less digits than its factorization.

81539188104 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 85339 (or 85335 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 48.

The spelling of 81539188104 in words is "eighty-one billion, five hundred thirty-nine million, one hundred eighty-eight thousand, one hundred four".