21322821 has 8 divisors (see below), whose sum is σ = 30617440. Its totient is φ = 13121712.

The previous prime is 21322799. The next prime is 21322849. The reversal of 21322821 is 12822312.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21322821 - 2⁶ = 21322757 is a prime.

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 (21322871) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 273331 + ... + 273408.

It is an arithmetic number, because the mean of its divisors is an integer number (3827180).

Almost surely, 2^21322821 is an apocalyptic number.

It is an amenable number.

21322821 is a deficient number, since it is larger than the sum of its proper divisors (9294619).

21322821 is a wasteful number, since it uses less digits than its factorization.

21322821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 546755.

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

The square root of 21322821 is about 4617.6640198265. The cubic root of 21322821 is about 277.2989469753.

The spelling of 21322821 in words is "twenty-one million, three hundred twenty-two thousand, eight hundred twenty-one".