71381 has 4 divisors (see below), whose sum is σ = 73164. Its totient is φ = 69600.

The previous prime is 71363. The next prime is 71387. The reversal of 71381 is 18317.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18317 = 13 ⋅1409.

It can be written as a sum of positive squares in 2 ways, for example, as 1156 + 70225 = 34^2 + 265^2 .

It is a cyclic number.

It is not a de Polignac number, because 71381 - 2⁶ = 71317 is a prime.

It is a super-2 number, since 2×71381² = 10190494322, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (71387) 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, 830 + ... + 911.

It is an arithmetic number, because the mean of its divisors is an integer number (18291).

2⁷¹³⁸¹ is an apocalyptic number.

It is an amenable number.

71381 is a deficient number, since it is larger than the sum of its proper divisors (1783).

71381 is a wasteful number, since it uses less digits than its factorization.

71381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1782.

The product of its digits is 168, while the sum is 20.

The square root of 71381 is about 267.1722290958. The cubic root of 71381 is about 41.4821135482.

Adding to 71381 its reverse (18317), we get a palindrome (89698).

The spelling of 71381 in words is "seventy-one thousand, three hundred eighty-one".