81957 has 8 divisors (see below), whose sum is σ = 115776. Its totient is φ = 51392.

The previous prime is 81953. The next prime is 81967. The reversal of 81957 is 75918.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81957 - 2² = 81953 is a prime.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81953) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 753 + ... + 854.

It is an arithmetic number, because the mean of its divisors is an integer number (14472).

2⁸¹⁹⁵⁷ is an apocalyptic number.

It is an amenable number.

81957 is a deficient number, since it is larger than the sum of its proper divisors (33819).

81957 is a wasteful number, since it uses less digits than its factorization.

81957 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1627.

The product of its digits is 2520, while the sum is 30.

The square root of 81957 is about 286.2813301632. The cubic root of 81957 is about 43.4372195175.

The spelling of 81957 in words is "eighty-one thousand, nine hundred fifty-seven".