1821881 has 4 divisors (see below), whose sum is σ = 1824912. Its totient is φ = 1818852.

The previous prime is 1821877. The next prime is 1821893. The reversal of 1821881 is 1881281.

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: 1881281 = 487 ⋅3863.

It is a cyclic number.

It is not a de Polignac number, because 1821881 - 2² = 1821877 is a prime.

It is a super-2 number, since 2×1821881² = 6638500756322, which contains 22 as substring.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1821821) 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, 275 + ... + 1928.

It is an arithmetic number, because the mean of its divisors is an integer number (456228).

2^1821881 is an apocalyptic number.

It is an amenable number.

1821881 is a deficient number, since it is larger than the sum of its proper divisors (3031).

1821881 is an equidigital number, since it uses as much as digits as its factorization.

1821881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3030.

The product of its digits is 1024, while the sum is 29.

The square root of 1821881 is about 1349.7707212708. The cubic root of 1821881 is about 122.1349621726.

The spelling of 1821881 in words is "one million, eight hundred twenty-one thousand, eight hundred eighty-one".