21921792 has 64 divisors (see below), whose sum is σ = 58719360. Its totient is φ = 7274496.

The previous prime is 21921773. The next prime is 21921803. The reversal of 21921792 is 29712912.

It is a tau number, because it is divible by the number of its divisors (64).

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 98193 + ... + 98415.

It is an arithmetic number, because the mean of its divisors is an integer number (917490).

Almost surely, 2^21921792 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 21921792, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (29359680).

21921792 is an abundant number, since it is smaller than the sum of its proper divisors (36797568).

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

21921792 is an frugal number, since it uses more digits than its factorization.

21921792 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 256 (or 228 counting only the distinct ones).

The product of its digits is 4536, while the sum is 33.

The square root of 21921792 is about 4682.0713364920. The cubic root of 21921792 is about 279.8715056678.

The spelling of 21921792 in words is "twenty-one million, nine hundred twenty-one thousand, seven hundred ninety-two".