1806641 has 4 divisors (see below), whose sum is σ = 1912932. Its totient is φ = 1700352.

The previous prime is 1806631. The next prime is 1806643. The reversal of 1806641 is 1466081.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1466081 = 419 ⋅3499.

It can be written as a sum of positive squares in 2 ways, for example, as 495616 + 1311025 = 704^2 + 1145^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1806641 is a prime.

It is a super-3 number, since 3×1806641³ = 17690366905333898163, which contains 333 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1806641.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1806643) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 53120 + ... + 53153.

It is an arithmetic number, because the mean of its divisors is an integer number (478233).

2^1806641 is an apocalyptic number.

It is an amenable number.

1806641 is a deficient number, since it is larger than the sum of its proper divisors (106291).

1806641 is a wasteful number, since it uses less digits than its factorization.

1806641 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 106290.

The product of its (nonzero) digits is 1152, while the sum is 26.

The square root of 1806641 is about 1344.1134624726. The cubic root of 1806641 is about 121.7934559502.

The spelling of 1806641 in words is "one million, eight hundred six thousand, six hundred forty-one".