21855845 has 8 divisors (see below), whose sum is σ = 28611360. Its totient is φ = 15895120.

The previous prime is 21855839. The next prime is 21855877. The reversal of 21855845 is 54855812.

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

It is not a de Polignac number, because 21855845 - 2⁶ = 21855781 is a prime.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21855799 and 21855808.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 198635 + ... + 198744.

It is an arithmetic number, because the mean of its divisors is an integer number (3576420).

Almost surely, 2^21855845 is an apocalyptic number.

It is an amenable number.

21855845 is a deficient number, since it is larger than the sum of its proper divisors (6755515).

21855845 is a wasteful number, since it uses less digits than its factorization.

21855845 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 397395.

The product of its digits is 64000, while the sum is 38.

The square root of 21855845 is about 4675.0235293526. The cubic root of 21855845 is about 279.5905793512.

The spelling of 21855845 in words is "twenty-one million, eight hundred fifty-five thousand, eight hundred forty-five".