21305532 has 24 divisors (see below), whose sum is σ = 50274000. Its totient is φ = 7021696.

The previous prime is 21305513. The next prime is 21305533. The reversal of 21305532 is 23550312.

It is a super-4 number, since 4×21305532⁴ (a number of 30 digits) contains 4444 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21305499 and 21305508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21305533) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8907 + ... + 11042.

It is an arithmetic number, because the mean of its divisors is an integer number (2094750).

Almost surely, 2^21305532 is an apocalyptic number.

It is an amenable number.

21305532 is an abundant number, since it is smaller than the sum of its proper divisors (28968468).

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

21305532 is a wasteful number, since it uses less digits than its factorization.

21305532 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20045 (or 20043 counting only the distinct ones).

The product of its (nonzero) digits is 900, while the sum is 21.

The square root of 21305532 is about 4615.7915897493. The cubic root of 21305532 is about 277.2239800681.

Adding to 21305532 its reverse (23550312), we get a palindrome (44855844).

The spelling of 21305532 in words is "twenty-one million, three hundred five thousand, five hundred thirty-two".