2099821 has 2 divisors, whose sum is σ = 2099822. Its totient is φ = 2099820.

The previous prime is 2099809. The next prime is 2099827. The reversal of 2099821 is 1289902.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1990921 + 108900 = 1411^2 + 330^2 .

It is a cyclic number.

It is not a de Polignac number, because 2099821 - 2⁹ = 2099309 is a prime.

It is a nialpdrome in base 12.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2099827) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1049910 + 1049911.

It is an arithmetic number, because the mean of its divisors is an integer number (1049911).

2^2099821 is an apocalyptic number.

It is an amenable number.

2099821 is a deficient number, since it is larger than the sum of its proper divisors (1).

2099821 is an equidigital number, since it uses as much as digits as its factorization.

2099821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2592, while the sum is 31.

The square root of 2099821 is about 1449.0759124352. The cubic root of 2099821 is about 128.0542779244.

The spelling of 2099821 in words is "two million, ninety-nine thousand, eight hundred twenty-one".