21432005 has 16 divisors (see below), whose sum is σ = 30342144. Its totient is φ = 14221440.

The previous prime is 21431983. The next prime is 21432013. The reversal of 21432005 is 50023412.

It is not a de Polignac number, because 21432005 - 2⁸ = 21431749 is a prime.

It is a Curzon number.

It is a congruent number.

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 in 15 ways as a sum of consecutive naturals, for example, 8792 + ... + 10961.

It is an arithmetic number, because the mean of its divisors is an integer number (1896384).

Almost surely, 2^21432005 is an apocalyptic number.

It is an amenable number.

21432005 is a deficient number, since it is larger than the sum of its proper divisors (8910139).

21432005 is a wasteful number, since it uses less digits than its factorization.

21432005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19796.

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 21432005 is about 4629.4713521092. The cubic root of 21432005 is about 277.7714466409.

Adding to 21432005 its reverse (50023412), we get a palindrome (71455417).

The spelling of 21432005 in words is "twenty-one million, four hundred thirty-two thousand, five".