420905 has 4 divisors (see below), whose sum is σ = 505092. Its totient is φ = 336720.

The previous prime is 420899. The next prime is 420919. The reversal of 420905 is 509024.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 326041 + 94864 = 571^2 + 308^2 .

It is not a de Polignac number, because 420905 - 2¹⁸ = 158761 is a prime.

It is a super-2 number, since 2×420905² = 354322038050, which contains 22 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 42086 + ... + 42095.

It is an arithmetic number, because the mean of its divisors is an integer number (126273).

2⁴²⁰⁹⁰⁵ is an apocalyptic number.

It is an amenable number.

420905 is a deficient number, since it is larger than the sum of its proper divisors (84187).

420905 is an equidigital number, since it uses as much as digits as its factorization.

420905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84186.

The product of its (nonzero) digits is 360, while the sum is 20.

The square root of 420905 is about 648.7719167782. The cubic root of 420905 is about 74.9424744072.

Adding to 420905 its reverse (509024), we get a palindrome (929929).

The spelling of 420905 in words is "four hundred twenty thousand, nine hundred five".