21432808 has 8 divisors (see below), whose sum is σ = 40186530. Its totient is φ = 10716400.

The previous prime is 21432793. The next prime is 21432809. The reversal of 21432808 is 80823412.

It can be written as a sum of positive squares in only one way, i.e., 12659364 + 8773444 = 3558^2 + 2962^2 .

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

It is a hoax number, since the sum of its digits (28) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21432809) 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 as a sum of consecutive naturals, namely, 1339543 + ... + 1339558.

Almost surely, 2^21432808 is an apocalyptic number.

It is an amenable number.

21432808 is a deficient number, since it is larger than the sum of its proper divisors (18753722).

21432808 is a wasteful number, since it uses less digits than its factorization.

21432808 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2679107 (or 2679103 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 28.

The square root of 21432808 is about 4629.5580782619. The cubic root of 21432808 is about 277.7749157157.

The spelling of 21432808 in words is "twenty-one million, four hundred thirty-two thousand, eight hundred eight".