21243264 has 96 divisors (see below), whose sum is σ = 65698200. Its totient is φ = 6064128.

The previous prime is 21243263. The next prime is 21243293. The reversal of 21243264 is 46234212.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21243263) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 18252 + ... + 19380.

Almost surely, 2^21243264 is an apocalyptic number.

21243264 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21243264, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32849100).

21243264 is an abundant number, since it is smaller than the sum of its proper divisors (44454936).

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

21243264 is a wasteful number, since it uses less digits than its factorization.

21243264 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1160 (or 1141 counting only the distinct ones).

The product of its digits is 2304, while the sum is 24.

The square root of 21243264 is about 4609.0415489557. The cubic root of 21243264 is about 276.9536429699.

Adding to 21243264 its reverse (46234212), we get a palindrome (67477476).

The spelling of 21243264 in words is "twenty-one million, two hundred forty-three thousand, two hundred sixty-four".