21321536 has 28 divisors (see below), whose sum is σ = 44801028. Its totient is φ = 10033152.

The previous prime is 21321527. The next prime is 21321539. The reversal of 21321536 is 63512312.

It can be written as a sum of positive squares in 2 ways, for example, as 12559936 + 8761600 = 3544^2 + 2960^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21321539) 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, 8711 + ... + 10886.

Almost surely, 2^21321536 is an apocalyptic number.

It is an amenable number.

21321536 is an abundant number, since it is smaller than the sum of its proper divisors (23479492).

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

21321536 is a wasteful number, since it uses less digits than its factorization.

21321536 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19626 (or 19616 counting only the distinct ones).

The product of its digits is 1080, while the sum is 23.

The square root of 21321536 is about 4617.5248781138. The cubic root of 21321536 is about 277.2933764756.

Adding to 21321536 its reverse (63512312), we get a palindrome (84833848).

The spelling of 21321536 in words is "twenty-one million, three hundred twenty-one thousand, five hundred thirty-six".