81599401880 has 64 divisors (see below), whose sum is σ = 188949637440. Its totient is φ = 31692114432.

The previous prime is 81599401867. The next prime is 81599401883. The reversal of 81599401880 is 8810499518.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81599401883) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 664154 + ... + 777366.

It is an arithmetic number, because the mean of its divisors is an integer number (2952338085).

Almost surely, 2^81599401880 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 81599401880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (94474818720).

81599401880 is an abundant number, since it is smaller than the sum of its proper divisors (107350235560).

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

81599401880 is a wasteful number, since it uses less digits than its factorization.

81599401880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 113748 (or 113744 counting only the distinct ones).

The product of its (nonzero) digits is 829440, while the sum is 53.

The spelling of 81599401880 in words is "eighty-one billion, five hundred ninety-nine million, four hundred one thousand, eight hundred eighty".