21819688 has 24 divisors (see below), whose sum is σ = 44971290. Its totient is φ = 9917600.

The previous prime is 21819683. The next prime is 21819713. The reversal of 21819688 is 88691812.

It can be written as a sum of positive squares in only one way, i.e., 15856324 + 5963364 = 3982^2 + 2442^2 .

It is not an unprimeable number, because it can be changed into a prime (21819683) by changing a digit.

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 5 ways as a sum of consecutive naturals, for example, 10303 + ... + 12238.

Almost surely, 2^21819688 is an apocalyptic number.

It is an amenable number.

21819688 is an abundant number, since it is smaller than the sum of its proper divisors (23151602).

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

21819688 is a wasteful number, since it uses less digits than its factorization.

21819688 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22569 (or 22554 counting only the distinct ones).

The product of its digits is 55296, while the sum is 43.

The square root of 21819688 is about 4671.1548893181. The cubic root of 21819688 is about 279.4363149524.

The spelling of 21819688 in words is "twenty-one million, eight hundred nineteen thousand, six hundred eighty-eight".