549721 has 4 divisors (see below), whose sum is σ = 552244. Its totient is φ = 547200.

The previous prime is 549719. The next prime is 549733. The reversal of 549721 is 127945.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 127945 = 5 ⋅25589.

It can be written as a sum of positive squares in 2 ways, for example, as 373321 + 176400 = 611^2 + 420^2 .

It is a cyclic number.

It is not a de Polignac number, because 549721 - 2¹ = 549719 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 549721.

It is not an unprimeable number, because it can be changed into a prime (549701) 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, 900 + ... + 1381.

It is an arithmetic number, because the mean of its divisors is an integer number (138061).

2⁵⁴⁹⁷²¹ is an apocalyptic number.

It is an amenable number.

549721 is a deficient number, since it is larger than the sum of its proper divisors (2523).

549721 is a wasteful number, since it uses less digits than its factorization.

549721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2522.

The product of its digits is 2520, while the sum is 28.

The square root of 549721 is about 741.4317230872. The cubic root of 549721 is about 81.9182707390.

The spelling of 549721 in words is "five hundred forty-nine thousand, seven hundred twenty-one".