21487812 has 12 divisors (see below), whose sum is σ = 50138256. Its totient is φ = 7162600.

The previous prime is 21487783. The next prime is 21487891. The reversal of 21487812 is 21878412.

It is a happy number.

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

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 895314 + ... + 895337.

It is an arithmetic number, because the mean of its divisors is an integer number (4178188).

Almost surely, 2^21487812 is an apocalyptic number.

It is an amenable number.

21487812 is an abundant number, since it is smaller than the sum of its proper divisors (28650444).

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

21487812 is a wasteful number, since it uses less digits than its factorization.

21487812 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1790658 (or 1790656 counting only the distinct ones).

The product of its digits is 7168, while the sum is 33.

The square root of 21487812 is about 4635.4947955963. The cubic root of 21487812 is about 278.0123349081.

The spelling of 21487812 in words is "twenty-one million, four hundred eighty-seven thousand, eight hundred twelve".