556421 has 4 divisors (see below), whose sum is σ = 558144. Its totient is φ = 554700.

The previous prime is 556403. The next prime is 556441. The reversal of 556421 is 124655.

556421 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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.

It is a cyclic number.

It is not a de Polignac number, because 556421 - 2¹⁸ = 294277 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (556441) 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, 215 + ... + 1076.

It is an arithmetic number, because the mean of its divisors is an integer number (139536).

2⁵⁵⁶⁴²¹ is an apocalyptic number.

556421 is the 431-st octagonal number.

It is an amenable number.

556421 is a deficient number, since it is larger than the sum of its proper divisors (1723).

556421 is a wasteful number, since it uses less digits than its factorization.

556421 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1722.

The product of its digits is 1200, while the sum is 23.

The square root of 556421 is about 745.9363243602. The cubic root of 556421 is about 82.2497343881.

The spelling of 556421 in words is "five hundred fifty-six thousand, four hundred twenty-one".