21138343 has 4 divisors (see below), whose sum is σ = 21496680. Its totient is φ = 20780008.

The previous prime is 21138319. The next prime is 21138353. The reversal of 21138343 is 34383112.

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-21138343 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 (21138353) 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, 179080 + ... + 179197.

It is an arithmetic number, because the mean of its divisors is an integer number (5374170).

Almost surely, 2^21138343 is an apocalyptic number.

21138343 is a deficient number, since it is larger than the sum of its proper divisors (358337).

21138343 is an equidigital number, since it uses as much as digits as its factorization.

21138343 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 358336.

The product of its digits is 1728, while the sum is 25.

The square root of 21138343 is about 4597.6453756244. The cubic root of 21138343 is about 276.4969299669.

The spelling of 21138343 in words is "twenty-one million, one hundred thirty-eight thousand, three hundred forty-three".