81137738880 has 768 divisors, whose sum is σ = 324635351040. Its totient is φ = 19194900480.

The previous prime is 81137738879. The next prime is 81137738897. The reversal of 81137738880 is 8883773118.

81137738880 is a `hidden beast` number, since 8 + 113 + 77 + 388 + 80 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 73560409 + ... + 73561511.

It is an arithmetic number, because the mean of its divisors is an integer number (422702280).

Almost surely, 2^81137738880 is an apocalyptic number.

81137738880 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81137738880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (162317675520).

81137738880 is an abundant number, since it is smaller than the sum of its proper divisors (243497612160).

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

81137738880 is a wasteful number, since it uses less digits than its factorization.

81137738880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1191 (or 1167 counting only the distinct ones).

The product of its (nonzero) digits is 1806336, while the sum is 54.

The spelling of 81137738880 in words is "eighty-one billion, one hundred thirty-seven million, seven hundred thirty-eight thousand, eight hundred eighty".