2081821 has 4 divisors (see below), whose sum is σ = 2379232. Its totient is φ = 1784412.

The previous prime is 2081813. The next prime is 2081831. The reversal of 2081821 is 1281802.

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: 1281802 = 2 ⋅640901.

It is not a de Polignac number, because 2081821 - 2³ = 2081813 is a prime.

It is a pancake number, because a pancake can be divided into 2081821 parts by 2040 straight cuts.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 2081792 and 2081801.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (2081801) 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, 148695 + ... + 148708.

It is an arithmetic number, because the mean of its divisors is an integer number (594808).

2^2081821 is an apocalyptic number.

It is an amenable number.

2081821 is a deficient number, since it is larger than the sum of its proper divisors (297411).

2081821 is an equidigital number, since it uses as much as digits as its factorization.

2081821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 297410.

The product of its (nonzero) digits is 256, while the sum is 22.

The square root of 2081821 is about 1442.8516902301. The cubic root of 2081821 is about 127.6873268432.

The spelling of 2081821 in words is "two million, eighty-one thousand, eight hundred twenty-one".