21841805 has 8 divisors (see below), whose sum is σ = 26348544. Its totient is φ = 17381200.

The previous prime is 21841751. The next prime is 21841817. The reversal of 21841805 is 50814812.

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

It is not a de Polignac number, because 21841805 - 2¹² = 21837709 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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, 10481 + ... + 12390.

It is an arithmetic number, because the mean of its divisors is an integer number (3293568).

Almost surely, 2^21841805 is an apocalyptic number.

It is an amenable number.

21841805 is a deficient number, since it is larger than the sum of its proper divisors (4506739).

21841805 is a wasteful number, since it uses less digits than its factorization.

21841805 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23067.

The product of its (nonzero) digits is 2560, while the sum is 29.

The square root of 21841805 is about 4673.5216914015. The cubic root of 21841805 is about 279.5306976950.

The spelling of 21841805 in words is "twenty-one million, eight hundred forty-one thousand, eight hundred five".