1806409 has 6 divisors (see below), whose sum is σ = 1985690. Its totient is φ = 1642080.

The previous prime is 1806407. The next prime is 1806421. The reversal of 1806409 is 9046081.

It can be written as a sum of positive squares in only one way, i.e., 1742400 + 64009 = 1320^2 + 253^2 .

It is not a de Polignac number, because 1806409 - 2¹ = 1806407 is a prime.

It is a super-2 number, since 2×1806409² = 6526226950562, which contains 22 as substring.

It is a Duffinian number.

1806409 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1806407) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7344 + ... + 7585.

2^1806409 is an apocalyptic number.

It is an amenable number.

1806409 is a deficient number, since it is larger than the sum of its proper divisors (179281).

1806409 is a wasteful number, since it uses less digits than its factorization.

1806409 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14951 (or 14940 counting only the distinct ones).

The product of its (nonzero) digits is 1728, while the sum is 28.

The square root of 1806409 is about 1344.0271574637. The cubic root of 1806409 is about 121.7882423537.

The spelling of 1806409 in words is "one million, eight hundred six thousand, four hundred nine".