21321143 has 4 divisors (see below), whose sum is σ = 21334320. Its totient is φ = 21307968.

The previous prime is 21321133. The next prime is 21321169. The reversal of 21321143 is 34112312.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21321143 - 2¹⁶ = 21255607 is a prime.

It is a super-2 number, since 2×21321143² = 909182277652898, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321133) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3755 + ... + 7532.

It is an arithmetic number, because the mean of its divisors is an integer number (5333580).

Almost surely, 2^21321143 is an apocalyptic number.

21321143 is a deficient number, since it is larger than the sum of its proper divisors (13177).

21321143 is a wasteful number, since it uses less digits than its factorization.

21321143 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13176.

The product of its digits is 144, while the sum is 17.

The square root of 21321143 is about 4617.4823226516. The cubic root of 21321143 is about 277.2916727683.

Adding to 21321143 its reverse (34112312), we get a palindrome (55433455).

The spelling of 21321143 in words is "twenty-one million, three hundred twenty-one thousand, one hundred forty-three".