21001343 has 4 divisors (see below), whose sum is σ = 22910568. Its totient is φ = 19092120.

The previous prime is 21001319. The next prime is 21001349. The reversal of 21001343 is 34310012.

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 21001343 - 2⁸ = 21001087 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 (21001349) 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 3 ways as a sum of consecutive naturals, for example, 954596 + ... + 954617.

It is an arithmetic number, because the mean of its divisors is an integer number (5727642).

Almost surely, 2^21001343 is an apocalyptic number.

21001343 is a deficient number, since it is larger than the sum of its proper divisors (1909225).

21001343 is a wasteful number, since it uses less digits than its factorization.

21001343 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1909224.

The product of its (nonzero) digits is 72, while the sum is 14.

The square root of 21001343 is about 4582.7222259264. The cubic root of 21001343 is about 275.8982988384.

Adding to 21001343 its reverse (34310012), we get a palindrome (55311355).

It can be divided in two parts, 2100 and 1343, that added together give a palindrome (3443).

The spelling of 21001343 in words is "twenty-one million, one thousand, three hundred forty-three".