57721 has 4 divisors (see below), whose sum is σ = 58212. Its totient is φ = 57232.

The previous prime is 57719. The next prime is 57727. The reversal of 57721 is 12775.

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.

It can be written as a sum of positive squares in 2 ways, for example, as 55696 + 2025 = 236^2 + 45^2 .

It is a cyclic number.

It is not a de Polignac number, because 57721 - 2¹ = 57719 is a prime.

It is a Duffinian number.

Its product of digits (490) is a multiple of the sum of its prime divisors (490).

It is a junction number, because it is equal to n+sod(n) for n = 57692 and 57701.

It is not an unprimeable number, because it can be changed into a prime (57727) 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, 51 + ... + 343.

It is an arithmetic number, because the mean of its divisors is an integer number (14553).

2⁵⁷⁷²¹ is an apocalyptic number.

It is an amenable number.

57721 is a deficient number, since it is larger than the sum of its proper divisors (491).

57721 is a wasteful number, since it uses less digits than its factorization.

57721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 490.

The product of its digits is 490, while the sum is 22.

The square root of 57721 is about 240.2519510847. The cubic root of 57721 is about 38.6465991127.

The spelling of 57721 in words is "fifty-seven thousand, seven hundred twenty-one".