21831321 has 8 divisors (see below), whose sum is σ = 29294464. Its totient is φ = 14461200.

The previous prime is 21831263. The next prime is 21831353. The reversal of 21831321 is 12313812.

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

It is not a de Polignac number, because 21831321 - 2¹¹ = 21829273 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21831371) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 22705 + ... + 23646.

It is an arithmetic number, because the mean of its divisors is an integer number (3661808).

Almost surely, 2^21831321 is an apocalyptic number.

It is an amenable number.

21831321 is a deficient number, since it is larger than the sum of its proper divisors (7463143).

21831321 is a wasteful number, since it uses less digits than its factorization.

21831321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 46511.

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

The square root of 21831321 is about 4672.3999186713. The cubic root of 21831321 is about 279.4859659088.

The spelling of 21831321 in words is "twenty-one million, eight hundred thirty-one thousand, three hundred twenty-one".