21289906 has 16 divisors (see below), whose sum is σ = 35689248. Its totient is φ = 9440800.

The previous prime is 21289889. The next prime is 21289907. The reversal of 21289906 is 60998212.

It is not an unprimeable number, because it can be changed into a prime (21289907) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 10900 + ... + 12703.

It is an arithmetic number, because the mean of its divisors is an integer number (2230578).

Almost surely, 2^21289906 is an apocalyptic number.

21289906 is a deficient number, since it is larger than the sum of its proper divisors (14399342).

21289906 is a wasteful number, since it uses less digits than its factorization.

21289906 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23657.

The product of its (nonzero) digits is 15552, while the sum is 37.

The square root of 21289906 is about 4614.0986118634. The cubic root of 21289906 is about 277.1561892022.

The spelling of 21289906 in words is "twenty-one million, two hundred eighty-nine thousand, nine hundred six".