81708187 has 4 divisors (see below), whose sum is σ = 89136216. Its totient is φ = 74280160.

The previous prime is 81708181. The next prime is 81708217. The reversal of 81708187 is 78180718.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81708187 - 2⁷ = 81708059 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81708181) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3713998 + ... + 3714019.

It is an arithmetic number, because the mean of its divisors is an integer number (22284054).

Almost surely, 2^81708187 is an apocalyptic number.

81708187 is a deficient number, since it is larger than the sum of its proper divisors (7428029).

81708187 is a wasteful number, since it uses less digits than its factorization.

81708187 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7428028.

The product of its (nonzero) digits is 25088, while the sum is 40.

The square root of 81708187 is about 9039.2581000876. The cubic root of 81708187 is about 433.9321798645.

The spelling of 81708187 in words is "eighty-one million, seven hundred eight thousand, one hundred eighty-seven".