1821493 has 4 divisors (see below), whose sum is σ = 1827328. Its totient is φ = 1815660.

The previous prime is 1821487. The next prime is 1821497. The reversal of 1821493 is 3941281.

It is a happy number.

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: 3941281 = 71 ⋅55511.

It is a cyclic number.

It is not a de Polignac number, because 1821493 - 2¹⁷ = 1690421 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 (1821497) 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, 2421 + ... + 3082.

It is an arithmetic number, because the mean of its divisors is an integer number (456832).

2^1821493 is an apocalyptic number.

It is an amenable number.

1821493 is a deficient number, since it is larger than the sum of its proper divisors (5835).

1821493 is an equidigital number, since it uses as much as digits as its factorization.

1821493 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5834.

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

The square root of 1821493 is about 1349.6269855038. The cubic root of 1821493 is about 122.1262913300.

The spelling of 1821493 in words is "one million, eight hundred twenty-one thousand, four hundred ninety-three".