21323503 has 2 divisors, whose sum is σ = 21323504. Its totient is φ = 21323502.

The previous prime is 21323479. The next prime is 21323509. The reversal of 21323503 is 30532312.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21323503 - 2⁹ = 21322991 is a prime.

It is a plaindrome in base 16.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21323509) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10661751 + 10661752.

It is an arithmetic number, because the mean of its divisors is an integer number (10661752).

Almost surely, 2^21323503 is an apocalyptic number.

21323503 is a deficient number, since it is larger than the sum of its proper divisors (1).

21323503 is an equidigital number, since it uses as much as digits as its factorization.

21323503 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 21323503 is about 4617.7378660985. The cubic root of 21323503 is about 277.3019033675.

Adding to 21323503 its reverse (30532312), we get a palindrome (51855815).

It can be divided in two parts, 213 and 23503, that added together give a square (23716 = 154²).

The spelling of 21323503 in words is "twenty-one million, three hundred twenty-three thousand, five hundred three".