21806000 has 40 divisors (see below), whose sum is σ = 52731744. Its totient is φ = 8721600.

The previous prime is 21805997. The next prime is 21806003. The reversal of 21806000 is 60812.

It is an interprime number because it is at equal distance from previous prime (21805997) and next prime (21806003).

It is a tau number, because it is divible by the number of its divisors (40).

It is a self number, because there is not a number n which added to its sum of digits gives 21806000.

It is not an unprimeable number, because it can be changed into a prime (21806003) 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, 3452 + ... + 7451.

Almost surely, 2^21806000 is an apocalyptic number.

21806000 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

21806000 is an abundant number, since it is smaller than the sum of its proper divisors (30925744).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21806000 is a wasteful number, since it uses less digits than its factorization.

21806000 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10926 (or 10910 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 17.

The square root of 21806000 is about 4669.6894971722. The cubic root of 21806000 is about 279.3778704201.

Adding to 21806000 its reverse (60812), we get a palindrome (21866812).

The spelling of 21806000 in words is "twenty-one million, eight hundred six thousand".