81045222720 has 896 divisors, whose sum is σ = 330342727680. Its totient is φ = 16349921280.

The previous prime is 81045222719. The next prime is 81045222721. The reversal of 81045222720 is 2722254018.

It is an interprime number because it is at equal distance from previous prime (81045222719) and next prime (81045222721).

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81045222721) by changing a digit.

It is a polite number, since it can be written in 127 ways as a sum of consecutive naturals, for example, 638151297 + ... + 638151423.

It is an arithmetic number, because the mean of its divisors is an integer number (368686080).

Almost surely, 2^81045222720 is an apocalyptic number.

81045222720 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 81045222720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (165171363840).

81045222720 is an abundant number, since it is smaller than the sum of its proper divisors (249297504960).

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

81045222720 is a wasteful number, since it uses less digits than its factorization.

81045222720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 351 (or 341 counting only the distinct ones).

The product of its (nonzero) digits is 17920, while the sum is 33.

Adding to 81045222720 its reverse (2722254018), we get a palindrome (83767476738).

The spelling of 81045222720 in words is "eighty-one billion, forty-five million, two hundred twenty-two thousand, seven hundred twenty".