71657 has 4 divisors (see below), whose sum is σ = 72336. Its totient is φ = 70980.

The previous prime is 71647. The next prime is 71663. The reversal of 71657 is 75617.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 71657 - 2⁶ = 71593 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (71647) 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, 143 + ... + 404.

It is an arithmetic number, because the mean of its divisors is an integer number (18084).

2⁷¹⁶⁵⁷ is an apocalyptic number.

It is an amenable number.

71657 is a deficient number, since it is larger than the sum of its proper divisors (679).

71657 is a wasteful number, since it uses less digits than its factorization.

71657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 678.

The product of its digits is 1470, while the sum is 26.

The square root of 71657 is about 267.6882515166. The cubic root of 71657 is about 41.5355093572.

Subtracting from 71657 its sum of digits (26), we obtain a triangular number (71631 = T₃₇₈).

The spelling of 71657 in words is "seventy-one thousand, six hundred fifty-seven".