556921 has 4 divisors (see below), whose sum is σ = 562432. Its totient is φ = 551412.

The previous prime is 556891. The next prime is 556931. The reversal of 556921 is 129655.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 129655 = 5 ⋅25931.

It is a cyclic number.

It is not a de Polignac number, because 556921 - 2⁷ = 556793 is a prime.

It is a super-2 number, since 2×556921² = 620322000482, which contains 22 as substring.

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 556921.

It is not an unprimeable number, because it can be changed into a prime (556931) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2601 + ... + 2806.

It is an arithmetic number, because the mean of its divisors is an integer number (140608).

2⁵⁵⁶⁹²¹ is an apocalyptic number.

It is an amenable number.

556921 is a deficient number, since it is larger than the sum of its proper divisors (5511).

556921 is a wasteful number, since it uses less digits than its factorization.

556921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5510.

The product of its digits is 2700, while the sum is 28.

The square root of 556921 is about 746.2713983532. The cubic root of 556921 is about 82.2743635539.

The spelling of 556921 in words is "five hundred fifty-six thousand, nine hundred twenty-one".