21531412 has 12 divisors (see below), whose sum is σ = 43062880. Its totient is φ = 9227736.

The previous prime is 21531379. The next prime is 21531439. The reversal of 21531412 is 21413512.

21531412 is an admirable number.

It is a self number, because there is not a number n which added to its sum of digits gives 21531412.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 384462 + ... + 384517.

Almost surely, 2^21531412 is an apocalyptic number.

It is an amenable number.

21531412 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

21531412 is a wasteful number, since it uses less digits than its factorization.

21531412 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 768990 (or 768988 counting only the distinct ones).

The product of its digits is 240, while the sum is 19.

The square root of 21531412 is about 4640.1952545125. The cubic root of 21531412 is about 278.2002421852.

Adding to 21531412 its reverse (21413512), we get a palindrome (42944924).

The spelling of 21531412 in words is "twenty-one million, five hundred thirty-one thousand, four hundred twelve".