81802173180 has 384 divisors, whose sum is σ = 308124794880. Its totient is φ = 15719546880.

The previous prime is 81802173113. The next prime is 81802173191. The reversal of 81802173180 is 8137120818.

It is a super-2 number, since 2×81802173180² (a number of 23 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 2863206 + ... + 2891634.

It is an arithmetic number, because the mean of its divisors is an integer number (802408320).

Almost surely, 2^81802173180 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 81802173180, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (154062397440).

81802173180 is an abundant number, since it is smaller than the sum of its proper divisors (226322621700).

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

81802173180 is a wasteful number, since it uses less digits than its factorization.

81802173180 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 28509 (or 28507 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 39.

Adding to 81802173180 its reverse (8137120818), we get a palindrome (89939293998).

The spelling of 81802173180 in words is "eighty-one billion, eight hundred two million, one hundred seventy-three thousand, one hundred eighty".