21968784 has 90 divisors (see below), whose sum is σ = 64031058. Its totient is φ = 7027200.

The previous prime is 21968783. The next prime is 21968803. The reversal of 21968784 is 48786912.

It can be written as a sum of positive squares in 3 ways, for example, as 4928400 + 17040384 = 2220^2 + 4128^2 .

It is a zygodrome in base 11.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21968783) 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 17 ways as a sum of consecutive naturals, for example, 360114 + ... + 360174.

Almost surely, 2^21968784 is an apocalyptic number.

21968784 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 21968784, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32015529).

21968784 is an abundant number, since it is smaller than the sum of its proper divisors (42062274).

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

21968784 is a wasteful number, since it uses less digits than its factorization.

21968784 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177 (or 107 counting only the distinct ones).

The product of its digits is 193536, while the sum is 45.

The square root of 21968784 is about 4687.0869418008. The cubic root of 21968784 is about 280.0713423651.

It can be divided in two parts, 2196 and 8784, that multiplied together give a square (19289664 = 4392²).

The spelling of 21968784 in words is "twenty-one million, nine hundred sixty-eight thousand, seven hundred eighty-four".