20143821 has 4 divisors (see below), whose sum is σ = 26858432. Its totient is φ = 13429212.

The previous prime is 20143817. The next prime is 20143829. The reversal of 20143821 is 12834102.

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 20143821 - 2² = 20143817 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20143829) 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, 3357301 + ... + 3357306.

It is an arithmetic number, because the mean of its divisors is an integer number (6714608).

Almost surely, 2^20143821 is an apocalyptic number.

It is an amenable number.

20143821 is a deficient number, since it is larger than the sum of its proper divisors (6714611).

20143821 is an equidigital number, since it uses as much as digits as its factorization.

20143821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6714610.

The product of its (nonzero) digits is 384, while the sum is 21.

The square root of 20143821 is about 4488.1868276621. The cubic root of 20143821 is about 272.0908586673.

Adding to 20143821 its reverse (12834102), we get a palindrome (32977923).

The spelling of 20143821 in words is "twenty million, one hundred forty-three thousand, eight hundred twenty-one".