21843989 has 8 divisors (see below), whose sum is σ = 22764000. Its totient is φ = 20935152.

The previous prime is 21843979. The next prime is 21844001. The reversal of 21843989 is 98934812.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 21843989 - 2¹² = 21839893 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 (21843919) 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, 1322 + ... + 6740.

It is an arithmetic number, because the mean of its divisors is an integer number (2845500).

Almost surely, 2^21843989 is an apocalyptic number.

21843989 is a gapful number since it is divisible by the number (29) formed by its first and last digit.

It is an amenable number.

21843989 is a deficient number, since it is larger than the sum of its proper divisors (920011).

21843989 is a wasteful number, since it uses less digits than its factorization.

21843989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5587.

The product of its digits is 124416, while the sum is 44.

The square root of 21843989 is about 4673.7553423345. The cubic root of 21843989 is about 279.5400143043.

The spelling of 21843989 in words is "twenty-one million, eight hundred forty-three thousand, nine hundred eighty-nine".