71721 has 12 divisors (see below), whose sum is σ = 111748. Its totient is φ = 44064.

The previous prime is 71719. The next prime is 71741. The reversal of 71721 is 12717.

It can be written as a sum of positive squares in 2 ways, for example, as 3600 + 68121 = 60^2 + 261^2 .

It is not a de Polignac number, because 71721 - 2¹ = 71719 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 71694 and 71703.

It is not an unprimeable number, because it can be changed into a prime (71711) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 190 + ... + 423.

2⁷¹⁷²¹ is an apocalyptic number.

It is an amenable number.

71721 is a deficient number, since it is larger than the sum of its proper divisors (40027).

71721 is a wasteful number, since it uses less digits than its factorization.

71721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 632 (or 629 counting only the distinct ones).

The product of its digits is 98, while the sum is 18.

The square root of 71721 is about 267.8077668777. The cubic root of 71721 is about 41.5478714041.

It can be divided in two parts, 7 and 1721, that added together give a cube (1728 = 12³).

The spelling of 71721 in words is "seventy-one thousand, seven hundred twenty-one", and thus it is an iban number.