21921600 has 84 divisors (see below), whose sum is σ = 71936864. Its totient is φ = 5844480.

The previous prime is 21921577. The next prime is 21921607. The reversal of 21921600 is 612912.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21921607) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2517 + ... + 7083.

Almost surely, 2^21921600 is an apocalyptic number.

21921600 is a gapful number since it is divisible by the number (20) 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 21921600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (35968432).

21921600 is an abundant number, since it is smaller than the sum of its proper divisors (50015264).

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

21921600 is a wasteful number, since it uses less digits than its factorization.

21921600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4592 (or 4577 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 21.

The square root of 21921600 is about 4682.0508327014. The cubic root of 21921600 is about 279.8706885891.

The spelling of 21921600 in words is "twenty-one million, nine hundred twenty-one thousand, six hundred".