21813321 has 8 divisors (see below), whose sum is σ = 29119104. Its totient is φ = 14524880.

The previous prime is 21813301. The next prime is 21813331. The reversal of 21813321 is 12331812.

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

It is a cyclic number.

It is not a de Polignac number, because 21813321 - 2⁵ = 21813289 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21813301) 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, 1041 + ... + 6686.

It is an arithmetic number, because the mean of its divisors is an integer number (3639888).

Almost surely, 2^21813321 is an apocalyptic number.

It is an amenable number.

21813321 is a deficient number, since it is larger than the sum of its proper divisors (7305783).

21813321 is an equidigital number, since it uses as much as digits as its factorization.

21813321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8671.

The product of its digits is 288, while the sum is 21.

The square root of 21813321 is about 4670.4733164852. The cubic root of 21813321 is about 279.4091324052.

The spelling of 21813321 in words is "twenty-one million, eight hundred thirteen thousand, three hundred twenty-one".