805421 has 2 divisors, whose sum is σ = 805422. Its totient is φ = 805420.

The previous prime is 805403. The next prime is 805451. The reversal of 805421 is 124508.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 592900 + 212521 = 770^2 + 461^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-805421 is a prime.

It is a Chen prime.

It is an Ulam number.

It is a junction number, because it is equal to n+sod(n) for n = 805393 and 805402.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 805421.

It is not a weakly prime, because it can be changed into another prime (805451) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 402710 + 402711.

It is an arithmetic number, because the mean of its divisors is an integer number (402711).

2⁸⁰⁵⁴²¹ is an apocalyptic number.

It is an amenable number.

805421 is a deficient number, since it is larger than the sum of its proper divisors (1).

805421 is an equidigital number, since it uses as much as digits as its factorization.

805421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 320, while the sum is 20.

The square root of 805421 is about 897.4525057071. The cubic root of 805421 is about 93.0409885996.

Adding to 805421 its reverse (124508), we get a palindrome (929929).

The spelling of 805421 in words is "eight hundred five thousand, four hundred twenty-one".