21313321 has 8 divisors (see below), whose sum is σ = 21690144. Its totient is φ = 20939520.

The previous prime is 21313301. The next prime is 21313333. The reversal of 21313321 is 12331312.

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 21313321 - 2²³ = 12924713 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21313295 and 21313304.

It is not an unprimeable number, because it can be changed into a prime (21313301) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 16905 + ... + 18121.

It is an arithmetic number, because the mean of its divisors is an integer number (2711268).

Almost surely, 2^21313321 is an apocalyptic number.

It is an amenable number.

21313321 is a deficient number, since it is larger than the sum of its proper divisors (376823).

21313321 is a wasteful number, since it uses less digits than its factorization.

21313321 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1511.

The product of its digits is 108, while the sum is 16.

The square root of 21313321 is about 4616.6352465838. The cubic root of 21313321 is about 277.2577590024.

Adding to 21313321 its reverse (12331312), we get a palindrome (33644633).

Subtracting from 21313321 its reverse (12331312), we obtain a square (8982009 = 2997²).

The spelling of 21313321 in words is "twenty-one million, three hundred thirteen thousand, three hundred twenty-one".