21404288 has 16 divisors (see below), whose sum is σ = 42641610. Its totient is φ = 10702080.

The previous prime is 21404269. The next prime is 21404303. The reversal of 21404288 is 88240412.

It can be written as a sum of positive squares in only one way, i.e., 17372224 + 4032064 = 4168^2 + 2008^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is a self number, because there is not a number n which added to its sum of digits gives 21404288.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83483 + ... + 83738.

Almost surely, 2^21404288 is an apocalyptic number.

It is an amenable number.

21404288 is a deficient number, since it is larger than the sum of its proper divisors (21237322).

21404288 is an equidigital number, since it uses as much as digits as its factorization.

21404288 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 167235 (or 167223 counting only the distinct ones).

The product of its (nonzero) digits is 4096, while the sum is 29.

The square root of 21404288 is about 4626.4768452895. The cubic root of 21404288 is about 277.6516520862.

The spelling of 21404288 in words is "twenty-one million, four hundred four thousand, two hundred eighty-eight".