21636256 has 48 divisors (see below), whose sum is σ = 44089920. Its totient is φ = 10447360.

The previous prime is 21636227. The next prime is 21636259. The reversal of 21636256 is 65263612.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21636259) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 202155 + ... + 202261.

It is an arithmetic number, because the mean of its divisors is an integer number (918540).

Almost surely, 2^21636256 is an apocalyptic number.

It is an amenable number.

21636256 is an abundant number, since it is smaller than the sum of its proper divisors (22453664).

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

21636256 is a wasteful number, since it uses less digits than its factorization.

21636256 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 277 (or 269 counting only the distinct ones).

The product of its digits is 12960, while the sum is 31.

The square root of 21636256 is about 4651.4789046066. The cubic root of 21636256 is about 278.6510627721.

Adding to 21636256 its reverse (65263612), we get a palindrome (86899868).

The spelling of 21636256 in words is "twenty-one million, six hundred thirty-six thousand, two hundred fifty-six".