1099821 has 4 divisors (see below), whose sum is σ = 1466432. Its totient is φ = 733212.

The previous prime is 1099817. The next prime is 1099823. The reversal of 1099821 is 1289901.

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.

It is not a de Polignac number, because 1099821 - 2² = 1099817 is a prime.

It is a D-number.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1099823) 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, 183301 + ... + 183306.

It is an arithmetic number, because the mean of its divisors is an integer number (366608).

2^1099821 is an apocalyptic number.

It is an amenable number.

1099821 is a deficient number, since it is larger than the sum of its proper divisors (366611).

1099821 is an equidigital number, since it uses as much as digits as its factorization.

1099821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 366610.

The product of its (nonzero) digits is 1296, while the sum is 30.

The square root of 1099821 is about 1048.7235097966. The cubic root of 1099821 is about 103.2224119043. Note that the first 3 decimals are identical.

The spelling of 1099821 in words is "one million, ninety-nine thousand, eight hundred twenty-one".