421605 has 24 divisors (see below), whose sum is σ = 760032. Its totient is φ = 224208.

The previous prime is 421559. The next prime is 421607. The reversal of 421605 is 506124.

It is a happy number.

It is not a de Polignac number, because 421605 - 2⁸ = 421349 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (421607) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1042 + ... + 1388.

It is an arithmetic number, because the mean of its divisors is an integer number (31668).

2⁴²¹⁶⁰⁵ is an apocalyptic number.

421605 is a gapful number since it is divisible by the number (45) formed by its first and last digit.

It is an amenable number.

421605 is a deficient number, since it is larger than the sum of its proper divisors (338427).

421605 is an equidigital number, since it uses as much as digits as its factorization.

421605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 367 (or 355 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 421605 is about 649.3111734754. The cubic root of 421605 is about 74.9839965855.

Adding to 421605 its reverse (506124), we get a palindrome (927729).

It can be divided in two parts, 4 and 21605, that added together give a square (21609 = 147²).

The spelling of 421605 in words is "four hundred twenty-one thousand, six hundred five".