21323264 has 20 divisors (see below), whose sum is σ = 42605904. Its totient is φ = 10661376.

The previous prime is 21323261. The next prime is 21323273. The reversal of 21323264 is 46232312.

It is a super-4 number, since 4×21323264⁴ (a number of 30 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21323261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20312 + ... + 21335.

Almost surely, 2^21323264 is an apocalyptic number.

It is an amenable number.

21323264 is a deficient number, since it is larger than the sum of its proper divisors (21282640).

21323264 is an frugal number, since it uses more digits than its factorization.

21323264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 41665 (or 41649 counting only the distinct ones).

The product of its digits is 1728, while the sum is 23.

The square root of 21323264 is about 4617.7119875540. The cubic root of 21323264 is about 277.3008673369.

Adding to 21323264 its reverse (46232312), we get a palindrome (67555576).

The spelling of 21323264 in words is "twenty-one million, three hundred twenty-three thousand, two hundred sixty-four".