21987012 has 12 divisors (see below), whose sum is σ = 51303056. Its totient is φ = 7329000.

The previous prime is 21986989. The next prime is 21987019. The reversal of 21987012 is 21078912.

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 (21987019) 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, 916114 + ... + 916137.

Almost surely, 2^21987012 is an apocalyptic number.

It is an amenable number.

21987012 is an abundant number, since it is smaller than the sum of its proper divisors (29316044).

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

21987012 is a wasteful number, since it uses less digits than its factorization.

21987012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1832258 (or 1832256 counting only the distinct ones).

The product of its (nonzero) digits is 2016, while the sum is 30.

The square root of 21987012 is about 4689.0310299677. The cubic root of 21987012 is about 280.1487814733.

The spelling of 21987012 in words is "twenty-one million, nine hundred eighty-seven thousand, twelve".