81155743680 has 224 divisors, whose sum is σ = 290787978240. Its totient is φ = 18995630080.

The previous prime is 81155743673. The next prime is 81155743693. The reversal of 81155743680 is 8634755118.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is a congruent number.

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, 173737 + ... + 438743.

Almost surely, 2^81155743680 is an apocalyptic number.

81155743680 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 81155743680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (145393989120).

81155743680 is an abundant number, since it is smaller than the sum of its proper divisors (209632234560).

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

81155743680 is a wasteful number, since it uses less digits than its factorization.

81155743680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 265067 (or 265057 counting only the distinct ones).

The product of its (nonzero) digits is 806400, while the sum is 48.

The spelling of 81155743680 in words is "eighty-one billion, one hundred fifty-five million, seven hundred forty-three thousand, six hundred eighty".