81445320 has 192 divisors, whose sum is σ = 292818240. Its totient is φ = 19468800.

The previous prime is 81445279. The next prime is 81445349. The reversal of 81445320 is 2354418.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 518682 + ... + 518838.

It is an arithmetic number, because the mean of its divisors is an integer number (1525095).

Almost surely, 2^81445320 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 81445320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (146409120).

81445320 is an abundant number, since it is smaller than the sum of its proper divisors (211372920).

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

81445320 is a wasteful number, since it uses less digits than its factorization.

81445320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 316 (or 309 counting only the distinct ones).

The product of its (nonzero) digits is 3840, while the sum is 27.

The square root of 81445320 is about 9024.7060893970. The cubic root of 81445320 is about 433.4663391846.

Adding to 81445320 its reverse (2354418), we get a palindrome (83799738).

The spelling of 81445320 in words is "eighty-one million, four hundred forty-five thousand, three hundred twenty".