81409320 has 128 divisors (see below), whose sum is σ = 277833600. Its totient is φ = 21192192.

The previous prime is 81409309. The next prime is 81409337. The reversal of 81409320 is 2390418.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 45564 + ... + 47316.

It is an arithmetic number, because the mean of its divisors is an integer number (2170575).

Almost surely, 2^81409320 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 81409320, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (138916800).

81409320 is an abundant number, since it is smaller than the sum of its proper divisors (196424280).

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

81409320 is a wasteful number, since it uses less digits than its factorization.

81409320 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1816 (or 1806 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 27.

The square root of 81409320 is about 9022.7113441581. The cubic root of 81409320 is about 433.4024636587.

Adding to 81409320 its reverse (2390418), we get a palindrome (83799738).

The spelling of 81409320 in words is "eighty-one million, four hundred nine thousand, three hundred twenty".