21531484 has 72 divisors (see below), whose sum is σ = 45403008. Its totient is φ = 8864640.

The previous prime is 21531481. The next prime is 21531491. The reversal of 21531484 is 48413512.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21531481) 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 23 ways as a sum of consecutive naturals, for example, 581914 + ... + 581950.

Almost surely, 2^21531484 is an apocalyptic number.

It is an amenable number.

21531484 is an abundant number, since it is smaller than the sum of its proper divisors (23871524).

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

21531484 is a wasteful number, since it uses less digits than its factorization.

21531484 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123 (or 102 counting only the distinct ones).

The product of its digits is 3840, while the sum is 28.

The square root of 21531484 is about 4640.2030128002. The cubic root of 21531484 is about 278.2005522809.

Adding to 21531484 its reverse (48413512), we get a palindrome (69944996).

The spelling of 21531484 in words is "twenty-one million, five hundred thirty-one thousand, four hundred eighty-four".