1805213 has 4 divisors (see below), whose sum is σ = 1911420. Its totient is φ = 1699008.

The previous prime is 1805203. The next prime is 1805227. The reversal of 1805213 is 3125081.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 3125081 = 67 ⋅46643.

It can be written as a sum of positive squares in 2 ways, for example, as 964324 + 840889 = 982^2 + 917^2 .

It is a cyclic number.

It is not a de Polignac number, because 1805213 - 2¹² = 1801117 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1805203) 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, 53078 + ... + 53111.

It is an arithmetic number, because the mean of its divisors is an integer number (477855).

2^1805213 is an apocalyptic number.

It is an amenable number.

1805213 is a deficient number, since it is larger than the sum of its proper divisors (106207).

1805213 is a wasteful number, since it uses less digits than its factorization.

1805213 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 106206.

The product of its (nonzero) digits is 240, while the sum is 20.

The square root of 1805213 is about 1343.5821523078. The cubic root of 1805213 is about 121.7613582804.

The spelling of 1805213 in words is "one million, eight hundred five thousand, two hundred thirteen".