21843987 has 8 divisors (see below), whose sum is σ = 31773120. Its totient is φ = 13238760.

The previous prime is 21843979. The next prime is 21844001. The reversal of 21843987 is 78934812.

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

It is not a de Polignac number, because 21843987 - 2³ = 21843979 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21843937) 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, 330937 + ... + 331002.

It is an arithmetic number, because the mean of its divisors is an integer number (3971640).

Almost surely, 2^21843987 is an apocalyptic number.

21843987 is a deficient number, since it is larger than the sum of its proper divisors (9929133).

21843987 is a wasteful number, since it uses less digits than its factorization.

21843987 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 661953.

The product of its digits is 96768, while the sum is 42.

The square root of 21843987 is about 4673.7551283738. The cubic root of 21843987 is about 279.5400057729.

The spelling of 21843987 in words is "twenty-one million, eight hundred forty-three thousand, nine hundred eighty-seven".