21234564 has 108 divisors (see below), whose sum is σ = 61796644. Its totient is φ = 6110208.

The previous prime is 21234541. The next prime is 21234593. The reversal of 21234564 is 46543212.

It can be written as a sum of positive squares in 6 ways, for example, as 900 + 21233664 = 30^2 + 4608^2 .

Its product of digits (5760) is a multiple of the sum of its prime divisors (192).

It is an unprimeable number.

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 35 ways as a sum of consecutive naturals, for example, 135174 + ... + 135330.

Almost surely, 2^21234564 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21234564, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (30898322).

21234564 is an abundant number, since it is smaller than the sum of its proper divisors (40562080).

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

21234564 is a wasteful number, since it uses less digits than its factorization.

21234564 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 214 (or 192 counting only the distinct ones).

The product of its digits is 5760, while the sum is 27.

The square root of 21234564 is about 4608.0976552152. The cubic root of 21234564 is about 276.9158297961.

Adding to 21234564 its reverse (46543212), we get a palindrome (67777776).

The spelling of 21234564 in words is "twenty-one million, two hundred thirty-four thousand, five hundred sixty-four".