21002143 has 4 divisors (see below), whose sum is σ = 21047968. Its totient is φ = 20956320.

The previous prime is 21002129. The next prime is 21002203. The reversal of 21002143 is 34120012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21002143 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21002743) 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, 22218 + ... + 23143.

It is an arithmetic number, because the mean of its divisors is an integer number (5261992).

Almost surely, 2^21002143 is an apocalyptic number.

21002143 is a deficient number, since it is larger than the sum of its proper divisors (45825).

21002143 is an equidigital number, since it uses as much as digits as its factorization.

21002143 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 45824.

The product of its (nonzero) digits is 48, while the sum is 13.

The square root of 21002143 is about 4582.8095094603. The cubic root of 21002143 is about 275.9018020403.

Adding to 21002143 its reverse (34120012), we get a palindrome (55122155).

The spelling of 21002143 in words is "twenty-one million, two thousand, one hundred forty-three".