21808744 has 8 divisors (see below), whose sum is σ = 40891410. Its totient is φ = 10904368.

The previous prime is 21808729. The next prime is 21808753. The reversal of 21808744 is 44780812.

It can be written as a sum of positive squares in only one way, i.e., 13176900 + 8631844 = 3630^2 + 2938^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 1363039 + ... + 1363054.

Almost surely, 2^21808744 is an apocalyptic number.

It is an amenable number.

21808744 is a deficient number, since it is larger than the sum of its proper divisors (19082666).

21808744 is a wasteful number, since it uses less digits than its factorization.

21808744 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2726099 (or 2726095 counting only the distinct ones).

The product of its (nonzero) digits is 14336, while the sum is 34.

The square root of 21808744 is about 4669.9832976147. The cubic root of 21808744 is about 279.3895886127.

The spelling of 21808744 in words is "twenty-one million, eight hundred eight thousand, seven hundred forty-four".