21030912 has 144 divisors (see below), whose sum is σ = 69844320. Its totient is φ = 5971968.

The previous prime is 21030899. The next prime is 21030923. The reversal of 21030912 is 21903012.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 128943 + ... + 129105.

It is an arithmetic number, because the mean of its divisors is an integer number (485030).

Almost surely, 2^21030912 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21030912, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (34922160).

21030912 is an abundant number, since it is smaller than the sum of its proper divisors (48813408).

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

21030912 is a wasteful number, since it uses less digits than its factorization.

21030912 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198 (or 175 counting only the distinct ones).

The product of its (nonzero) digits is 108, while the sum is 18.

The square root of 21030912 is about 4585.9472303985. The cubic root of 21030912 is about 276.0277224832.

Adding to 21030912 its reverse (21903012), we get a palindrome (42933924).

The spelling of 21030912 in words is "twenty-one million, thirty thousand, nine hundred twelve".