21102321 has 32 divisors (see below), whose sum is σ = 31321728. Its totient is φ = 12579840.

The previous prime is 21102313. The next prime is 21102377. The reversal of 21102321 is 12320112.

It is not a de Polignac number, because 21102321 - 2³ = 21102313 is a prime.

21102321 is a modest number, since divided by 2321 gives 2110 as remainder.

It is a junction number, because it is equal to n+sod(n) for n = 21102297 and 21102306.

It is not an unprimeable number, because it can be changed into a prime (21102311) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 99906 + ... + 100116.

It is an arithmetic number, because the mean of its divisors is an integer number (978804).

Almost surely, 2^21102321 is an apocalyptic number.

It is an amenable number.

21102321 is a deficient number, since it is larger than the sum of its proper divisors (10219407).

21102321 is a wasteful number, since it uses less digits than its factorization.

21102321 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 321.

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 21102321 is about 4593.7262652448. The cubic root of 21102321 is about 276.3397805411.

Adding to 21102321 its reverse (12320112), we get a palindrome (33422433).

The spelling of 21102321 in words is "twenty-one million, one hundred two thousand, three hundred twenty-one".