21203543 has 2 divisors, whose sum is σ = 21203544. Its totient is φ = 21203542.

The previous prime is 21203513. The next prime is 21203579. The reversal of 21203543 is 34530212.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21203543 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21203503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10601771 + 10601772.

It is an arithmetic number, because the mean of its divisors is an integer number (10601772).

Almost surely, 2^21203543 is an apocalyptic number.

21203543 is a deficient number, since it is larger than the sum of its proper divisors (1).

21203543 is an equidigital number, since it uses as much as digits as its factorization.

21203543 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 720, while the sum is 20.

The square root of 21203543 is about 4604.7305024290. The cubic root of 21203543 is about 276.7809177973.

Adding to 21203543 its reverse (34530212), we get a palindrome (55733755).

The spelling of 21203543 in words is "twenty-one million, two hundred three thousand, five hundred forty-three".