21153536 has 36 divisors (see below), whose sum is σ = 44457000. Its totient is φ = 10017792.

The previous prime is 21153533. The next prime is 21153551. The reversal of 21153536 is 63535112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21153533) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 2690 + ... + 7038.

Almost surely, 2^21153536 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 21153536, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (22228500).

21153536 is an abundant number, since it is smaller than the sum of its proper divisors (23303464).

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

21153536 is an equidigital number, since it uses as much as digits as its factorization.

21153536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4384 (or 4370 counting only the distinct ones).

The product of its digits is 2700, while the sum is 26.

The square root of 21153536 is about 4599.2973376376. The cubic root of 21153536 is about 276.5631573564.

Adding to 21153536 its reverse (63535112), we get a palindrome (84688648).

The spelling of 21153536 in words is "twenty-one million, one hundred fifty-three thousand, five hundred thirty-six".