1801009 has 4 divisors (see below), whose sum is σ = 2058304. Its totient is φ = 1543716.

The previous prime is 1801003. The next prime is 1801013. The reversal of 1801009 is 9001081.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9001081 = 929 ⋅9689.

It is a cyclic number.

It is not a de Polignac number, because 1801009 - 2¹⁵ = 1768241 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1801003) by changing a digit.

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, 128637 + ... + 128650.

It is an arithmetic number, because the mean of its divisors is an integer number (514576).

2^1801009 is an apocalyptic number.

It is an amenable number.

1801009 is a deficient number, since it is larger than the sum of its proper divisors (257295).

1801009 is an equidigital number, since it uses as much as digits as its factorization.

1801009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 257294.

The product of its (nonzero) digits is 72, while the sum is 19.

The square root of 1801009 is about 1342.0167659161. The cubic root of 1801009 is about 121.6667650799. Note that the first 3 decimals are identical.

Adding to 1801009 its product of nonzero digits (72), we get a palindrome (1801081).

It can be divided in two parts, 180100 and 9, that multiplied together give a triangular number (1620900 = T₁₈₀₀).

The spelling of 1801009 in words is "one million, eight hundred one thousand, nine".