21323556 has 18 divisors (see below), whose sum is σ = 53901302. Its totient is φ = 7107840.

The previous prime is 21323531. The next prime is 21323591. The reversal of 21323556 is 65532312.

It can be written as a sum of positive squares in only one way, i.e., 19501056 + 1822500 = 4416^2 + 1350^2 .

It is a tau number, because it is divible by the number of its divisors (18).

It is a hoax number, since the sum of its digits (27) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 296125 + ... + 296196.

Almost surely, 2^21323556 is an apocalyptic number.

It is an amenable number.

21323556 is an abundant number, since it is smaller than the sum of its proper divisors (32577746).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21323556 is a wasteful number, since it uses less digits than its factorization.

21323556 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 592331 (or 592326 counting only the distinct ones).

The product of its digits is 5400, while the sum is 27.

The square root of 21323556 is about 4617.7436048356. The cubic root of 21323556 is about 277.3021331138.

Adding to 21323556 its reverse (65532312), we get a palindrome (86855868).

The spelling of 21323556 in words is "twenty-one million, three hundred twenty-three thousand, five hundred fifty-six".