421565 has 4 divisors (see below), whose sum is σ = 505884. Its totient is φ = 337248.

The previous prime is 421559. The next prime is 421607. The reversal of 421565 is 565124.

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 290521 + 131044 = 539^2 + 362^2 .

It is a cyclic number.

It is not a de Polignac number, because 421565 - 2⁶ = 421501 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 421565.

It is a congruent number.

It is an unprimeable number.

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, 42152 + ... + 42161.

It is an arithmetic number, because the mean of its divisors is an integer number (126471).

2⁴²¹⁵⁶⁵ is an apocalyptic number.

It is an amenable number.

421565 is a deficient number, since it is larger than the sum of its proper divisors (84319).

421565 is an equidigital number, since it uses as much as digits as its factorization.

421565 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84318.

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

The square root of 421565 is about 649.2803708722. The cubic root of 421565 is about 74.9816251282.

Adding to 421565 its reverse (565124), we get a palindrome (986689).

The spelling of 421565 in words is "four hundred twenty-one thousand, five hundred sixty-five".