21912864 has 96 divisors (see below), whose sum is σ = 63141120. Its totient is φ = 6623232.

The previous prime is 21912853. The next prime is 21912883. The reversal of 21912864 is 46821912.

It is a tau number, because it is divible by the number of its divisors (96).

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 15 ways as a sum of consecutive naturals, for example, 47097 + ... + 47559.

It is an arithmetic number, because the mean of its divisors is an integer number (657720).

Almost surely, 2^21912864 is an apocalyptic number.

21912864 is a gapful number since it is divisible by the number (24) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21912864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (31570560).

21912864 is an abundant number, since it is smaller than the sum of its proper divisors (41228256).

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

21912864 is a wasteful number, since it uses less digits than its factorization.

21912864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 522 (or 514 counting only the distinct ones).

The product of its digits is 6912, while the sum is 33.

The square root of 21912864 is about 4681.1178152232. The cubic root of 21912864 is about 279.8335064614.

The spelling of 21912864 in words is "twenty-one million, nine hundred twelve thousand, eight hundred sixty-four".