81317204220 has 288 divisors, whose sum is σ = 274700353536. Its totient is φ = 17902080000.

The previous prime is 81317204219. The next prime is 81317204231. The reversal of 81317204220 is 2240271318.

It is a super-4 number, since 4×81317204220⁴ (a number of 45 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (30).

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 95 ways as a sum of consecutive naturals, for example, 20322220 + ... + 20326220.

It is an arithmetic number, because the mean of its divisors is an integer number (953820672).

Almost surely, 2^81317204220 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 81317204220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (137350176768).

81317204220 is an abundant number, since it is smaller than the sum of its proper divisors (193383149316).

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

81317204220 is a wasteful number, since it uses less digits than its factorization.

81317204220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4281 (or 4272 counting only the distinct ones).

The product of its (nonzero) digits is 5376, while the sum is 30.

Adding to 81317204220 its reverse (2240271318), we get a palindrome (83557475538).

The spelling of 81317204220 in words is "eighty-one billion, three hundred seventeen million, two hundred four thousand, two hundred twenty".