21323555 has 24 divisors (see below), whose sum is σ = 28972944. Its totient is φ = 14940800.

The previous prime is 21323531. The next prime is 21323591. The reversal of 21323555 is 55532312.

It is not a de Polignac number, because 21323555 - 2²⁰ = 20274979 is a prime.

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 46025 + ... + 46485.

It is an arithmetic number, because the mean of its divisors is an integer number (1207206).

Almost surely, 2^21323555 is an apocalyptic number.

21323555 is a deficient number, since it is larger than the sum of its proper divisors (7649389).

21323555 is a wasteful number, since it uses less digits than its factorization.

21323555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 535 (or 506 counting only the distinct ones).

The product of its digits is 4500, while the sum is 26.

The square root of 21323555 is about 4617.7434965576. The cubic root of 21323555 is about 277.3021287790.

Adding to 21323555 its reverse (55532312), we get a palindrome (76855867).

The spelling of 21323555 in words is "twenty-one million, three hundred twenty-three thousand, five hundred fifty-five".