71857 has 4 divisors (see below), whose sum is σ = 72436. Its totient is φ = 71280.

The previous prime is 71849. The next prime is 71861. The reversal of 71857 is 75817.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 75817 = 7 ⋅10831.

It can be written as a sum of positive squares in 2 ways, for example, as 18496 + 53361 = 136^2 + 231^2 .

It is a cyclic number.

It is not a de Polignac number, because 71857 - 2³ = 71849 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71807) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18 + ... + 379.

It is an arithmetic number, because the mean of its divisors is an integer number (18109).

2⁷¹⁸⁵⁷ is an apocalyptic number.

It is an amenable number.

71857 is a deficient number, since it is larger than the sum of its proper divisors (579).

71857 is a wasteful number, since it uses less digits than its factorization.

71857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 578.

The product of its digits is 1960, while the sum is 28.

The square root of 71857 is about 268.0615600939. The cubic root of 71857 is about 41.5741163565.

The spelling of 71857 in words is "seventy-one thousand, eight hundred fifty-seven".