556721 has 12 divisors (see below), whose sum is σ = 632016. Its totient is φ = 489720.

The previous prime is 556709. The next prime is 556723. The reversal of 556721 is 127655.

It is not a de Polignac number, because 556721 - 2¹⁰ = 555697 is a prime.

It is not an unprimeable number, because it can be changed into a prime (556723) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5150 + ... + 5256.

It is an arithmetic number, because the mean of its divisors is an integer number (52668).

2⁵⁵⁶⁷²¹ is an apocalyptic number.

It is an amenable number.

556721 is a deficient number, since it is larger than the sum of its proper divisors (75295).

556721 is a wasteful number, since it uses less digits than its factorization.

556721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 172 (or 161 counting only the distinct ones).

The product of its digits is 2100, while the sum is 26.

The square root of 556721 is about 746.1373868129. The cubic root of 556721 is about 82.2645136572.

It can be divided in two parts, 55 and 6721, that added together give a palindrome (6776).

The spelling of 556721 in words is "five hundred fifty-six thousand, seven hundred twenty-one".