21303523 has 2 divisors, whose sum is σ = 21303524. Its totient is φ = 21303522.

The previous prime is 21303511. The next prime is 21303571. The reversal of 21303523 is 32530312.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21303523 - 2⁹ = 21303011 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21303523.

It is not a weakly prime, because it can be changed into another prime (21301523) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10651761 + 10651762.

It is an arithmetic number, because the mean of its divisors is an integer number (10651762).

Almost surely, 2^21303523 is an apocalyptic number.

21303523 is a deficient number, since it is larger than the sum of its proper divisors (1).

21303523 is an equidigital number, since it uses as much as digits as its factorization.

21303523 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 540, while the sum is 19.

The square root of 21303523 is about 4615.5739621417. The cubic root of 21303523 is about 277.2152662047.

Adding to 21303523 its reverse (32530312), we get a palindrome (53833835).

The spelling of 21303523 in words is "twenty-one million, three hundred three thousand, five hundred twenty-three".