21581484 has 12 divisors (see below), whose sum is σ = 50356824. Its totient is φ = 7193824.

The previous prime is 21581477. The next prime is 21581489. The reversal of 21581484 is 48418512.

It is a tau number, because it is divible by the number of its divisors (12).

It is not an unprimeable number, because it can be changed into a prime (21581489) 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, 899217 + ... + 899240.

It is an arithmetic number, because the mean of its divisors is an integer number (4196402).

Almost surely, 2^21581484 is an apocalyptic number.

It is an amenable number.

21581484 is an abundant number, since it is smaller than the sum of its proper divisors (28775340).

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

21581484 is a wasteful number, since it uses less digits than its factorization.

21581484 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1798464 (or 1798462 counting only the distinct ones).

The product of its digits is 10240, while the sum is 33.

The square root of 21581484 is about 4645.5875839338. The cubic root of 21581484 is about 278.4157298055.

Adding to 21581484 its reverse (48418512), we get a palindrome (69999996).

The spelling of 21581484 in words is "twenty-one million, five hundred eighty-one thousand, four hundred eighty-four".