1821387 has 4 divisors (see below), whose sum is σ = 2428520. Its totient is φ = 1214256.

The previous prime is 1821377. The next prime is 1821401. The reversal of 1821387 is 7831281.

It is a happy number.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 1821387 - 2⁴ = 1821371 is a prime.

It is a D-number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1821377) 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, 303562 + ... + 303567.

It is an arithmetic number, because the mean of its divisors is an integer number (607130).

2^1821387 is an apocalyptic number.

1821387 is a deficient number, since it is larger than the sum of its proper divisors (607133).

1821387 is an equidigital number, since it uses as much as digits as its factorization.

1821387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 607132.

The product of its digits is 2688, while the sum is 30.

The square root of 1821387 is about 1349.5877148226. The cubic root of 1821387 is about 122.1239222775.

The spelling of 1821387 in words is "one million, eight hundred twenty-one thousand, three hundred eighty-seven".