1809661 has 8 divisors (see below), whose sum is σ = 2076480. Its totient is φ = 1544928.

The previous prime is 1809631. The next prime is 1809671. The reversal of 1809661 is 1669081.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 1809661 - 2⁹ = 1809149 is a prime.

It is a nialpdrome in base 12.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1809601) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2625 + ... + 3241.

It is an arithmetic number, because the mean of its divisors is an integer number (259560).

2^1809661 is an apocalyptic number.

It is an amenable number.

1809661 is a deficient number, since it is larger than the sum of its proper divisors (266819).

1809661 is an equidigital number, since it uses as much as digits as its factorization.

1809661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1043.

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 1809661 is about 1345.2364104499. The cubic root of 1809661 is about 121.8612819098.

The spelling of 1809661 in words is "one million, eight hundred nine thousand, six hundred sixty-one".