81408 has 40 divisors (see below), whose sum is σ = 220968. Its totient is φ = 26624.

The previous prime is 81401. The next prime is 81409. The reversal of 81408 is 80418.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81401) by changing a digit.

81408 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1510 + ... + 1562.

2⁸¹⁴⁰⁸ 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 81408, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (110484).

81408 is an abundant number, since it is smaller than the sum of its proper divisors (139560).

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

81408 is an equidigital number, since it uses as much as digits as its factorization.

81408 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 74 (or 58 counting only the distinct ones).

The product of its (nonzero) digits is 256, while the sum is 21.

The square root of 81408 is about 285.3208720020. The cubic root of 81408 is about 43.3400121198.

Subtracting from 81408 its reverse (80418), we obtain a triangular number (990 = T₄₄).

The spelling of 81408 in words is "eighty-one thousand, four hundred eight".