81008 has 20 divisors (see below), whose sum is σ = 161448. Its totient is φ = 39360.

The previous prime is 81001. The next prime is 81013. The reversal of 81008 is 80018.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81001) by changing a digit.

81008 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, 935 + ... + 1017.

2⁸¹⁰⁰⁸ is an apocalyptic number.

It is an amenable number.

81008 is a deficient number, since it is larger than the sum of its proper divisors (80440).

81008 is a wasteful number, since it uses less digits than its factorization.

81008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 152 (or 146 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 17.

The square root of 81008 is about 284.6190436355. The cubic root of 81008 is about 43.2689115063.

Subtracting from 81008 its reverse (80018), we obtain a triangular number (990 = T₄₄).

The spelling of 81008 in words is "eighty-one thousand, eight".