21845999 has 4 divisors (see below), whose sum is σ = 24966864. Its totient is φ = 18725136.

The previous prime is 21845983. The next prime is 21846031. The reversal of 21845999 is 99954812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21845999 - 2⁴ = 21845983 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21845909) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1560422 + ... + 1560435.

It is an arithmetic number, because the mean of its divisors is an integer number (6241716).

Almost surely, 2^21845999 is an apocalyptic number.

21845999 is a deficient number, since it is larger than the sum of its proper divisors (3120865).

21845999 is an equidigital number, since it uses as much as digits as its factorization.

21845999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3120864.

The product of its digits is 233280, while the sum is 47.

The square root of 21845999 is about 4673.9703678992. The cubic root of 21845999 is about 279.5485881077.

The spelling of 21845999 in words is "twenty-one million, eight hundred forty-five thousand, nine hundred ninety-nine".