81907 has 4 divisors (see below), whose sum is σ = 93616. Its totient is φ = 70200.

The previous prime is 81901. The next prime is 81919. The reversal of 81907 is 70918.

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 81907 - 2³ = 81899 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81901) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5844 + ... + 5857.

It is an arithmetic number, because the mean of its divisors is an integer number (23404).

2⁸¹⁹⁰⁷ is an apocalyptic number.

81907 is a deficient number, since it is larger than the sum of its proper divisors (11709).

81907 is a wasteful number, since it uses less digits than its factorization.

81907 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11708.

The product of its (nonzero) digits is 504, while the sum is 25.

The square root of 81907 is about 286.1939901535. The cubic root of 81907 is about 43.4283843853.

The spelling of 81907 in words is "eighty-one thousand, nine hundred seven".