421905 has 16 divisors (see below), whose sum is σ = 736704. Its totient is φ = 204480.

The previous prime is 421891. The next prime is 421907. The reversal of 421905 is 509124.

It is not a de Polignac number, because 421905 - 2¹³ = 413713 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (421907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1114 + ... + 1443.

It is an arithmetic number, because the mean of its divisors is an integer number (46044).

2⁴²¹⁹⁰⁵ is an apocalyptic number.

It is an amenable number.

421905 is a deficient number, since it is larger than the sum of its proper divisors (314799).

421905 is a wasteful number, since it uses less digits than its factorization.

421905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2576.

The product of its (nonzero) digits is 360, while the sum is 21.

The square root of 421905 is about 649.5421464386. The cubic root of 421905 is about 75.0017777356.

It can be divided in two parts, 42190 and 5, that added together give a triangular number (42195 = T₂₉₀).

The spelling of 421905 in words is "four hundred twenty-one thousand, nine hundred five".