21806006 has 8 divisors (see below), whose sum is σ = 32864664. Its totient is φ = 10851120.

The previous prime is 21806003. The next prime is 21806011. The reversal of 21806006 is 60060812.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21806003) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 25415 + ... + 26258.

It is an arithmetic number, because the mean of its divisors is an integer number (4108083).

Almost surely, 2^21806006 is an apocalyptic number.

21806006 is a deficient number, since it is larger than the sum of its proper divisors (11058658).

21806006 is a wasteful number, since it uses less digits than its factorization.

21806006 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 51886.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 21806006 is about 4669.6901396131. The cubic root of 21806006 is about 279.3778960441.

Adding to 21806006 its reverse (60060812), we get a palindrome (81866818).

The spelling of 21806006 in words is "twenty-one million, eight hundred six thousand, six".