21929984 has 28 divisors (see below), whose sum is σ = 43873674. Its totient is φ = 10960896.

The previous prime is 21929977. The next prime is 21929987. The reversal of 21929984 is 48992912.

It can be written as a sum of positive squares in only one way, i.e., 21827584 + 102400 = 4672^2 + 320^2 .

It is not an unprimeable number, because it can be changed into a prime (21929987) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 6854 + ... + 9530.

Almost surely, 2^21929984 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 21929984, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21936837).

21929984 is an abundant number, since it is smaller than the sum of its proper divisors (21943690).

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

21929984 is an frugal number, since it uses more digits than its factorization.

21929984 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2703 (or 2679 counting only the distinct ones).

The product of its digits is 93312, while the sum is 44.

The square root of 21929984 is about 4682.9460812612. The cubic root of 21929984 is about 279.9063632476.

It can be divided in two parts, 219 and 29984, that added together give a palindrome (30203).

The spelling of 21929984 in words is "twenty-one million, nine hundred twenty-nine thousand, nine hundred eighty-four".