21844987 has 8 divisors (see below), whose sum is σ = 22776192. Its totient is φ = 20928000.

The previous prime is 21844969. The next prime is 21844993. The reversal of 21844987 is 78944812.

21844987 is nontrivially palindromic in base 12.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21844987 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21844937) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 358 + ... + 6619.

It is an arithmetic number, because the mean of its divisors is an integer number (2847024).

Almost surely, 2^21844987 is an apocalyptic number.

21844987 is a deficient number, since it is larger than the sum of its proper divisors (931205).

21844987 is a wasteful number, since it uses less digits than its factorization.

21844987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7109.

The product of its digits is 129024, while the sum is 43.

The square root of 21844987 is about 4673.8621075081. The cubic root of 21844987 is about 279.5442714127.

The spelling of 21844987 in words is "twenty-one million, eight hundred forty-four thousand, nine hundred eighty-seven".