21128912 has 40 divisors (see below), whose sum is σ = 49252800. Its totient is φ = 8577792.

The previous prime is 21128873. The next prime is 21128917. The reversal of 21128912 is 21982112.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21128917) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2837 + ... + 7092.

It is an arithmetic number, because the mean of its divisors is an integer number (1231320).

Almost surely, 2^21128912 is an apocalyptic number.

It is an amenable number.

21128912 is an abundant number, since it is smaller than the sum of its proper divisors (28123888).

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

21128912 is a wasteful number, since it uses less digits than its factorization.

21128912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9963 (or 9957 counting only the distinct ones).

The product of its digits is 576, while the sum is 26.

The square root of 21128912 is about 4596.6196275089. The cubic root of 21128912 is about 276.4558035890.

The spelling of 21128912 in words is "twenty-one million, one hundred twenty-eight thousand, nine hundred twelve".