21087912 has 16 divisors (see below), whose sum is σ = 52719840. Its totient is φ = 7029296.

The previous prime is 21087889. The next prime is 21087917. The reversal of 21087912 is 21978012.

It is a super-3 number, since 3×21087912³ (a number of 23 digits) contains 333 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21087912.

It is not an unprimeable number, because it can be changed into a prime (21087917) 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, 439308 + ... + 439355.

It is an arithmetic number, because the mean of its divisors is an integer number (3294990).

Almost surely, 2^21087912 is an apocalyptic number.

It is an amenable number.

21087912 is an abundant number, since it is smaller than the sum of its proper divisors (31631928).

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

21087912 is a wasteful number, since it uses less digits than its factorization.

21087912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 878672 (or 878668 counting only the distinct ones).

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

The square root of 21087912 is about 4592.1576627986. The cubic root of 21087912 is about 276.2768698228.

The spelling of 21087912 in words is "twenty-one million, eighty-seven thousand, nine hundred twelve".