401809 has 2 divisors, whose sum is σ = 401810. Its totient is φ = 401808.

The previous prime is 401773. The next prime is 401813. The reversal of 401809 is 908104.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 313600 + 88209 = 560^2 + 297^2 .

It is a cyclic number.

It is not a de Polignac number, because 401809 - 2¹¹ = 399761 is a prime.

It is a super-2 number, since 2×401809² = 322900944962, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 401809.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 401809.

It is not a weakly prime, because it can be changed into another prime (401839) 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 as a sum of consecutive naturals, namely, 200904 + 200905.

It is an arithmetic number, because the mean of its divisors is an integer number (200905).

2⁴⁰¹⁸⁰⁹ is an apocalyptic number.

It is an amenable number.

401809 is a deficient number, since it is larger than the sum of its proper divisors (1).

401809 is an equidigital number, since it uses as much as digits as its factorization.

401809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 288, while the sum is 22.

The square root of 401809 is about 633.8840587994. The cubic root of 401809 is about 73.7915364986.

It can be divided in two parts, 40 and 1809, that added together give a square (1849 = 43²).

The spelling of 401809 in words is "four hundred one thousand, eight hundred nine".