21984427 has 4 divisors (see below), whose sum is σ = 22004136. Its totient is φ = 21964720.

The previous prime is 21984421. The next prime is 21984449. The reversal of 21984427 is 72448912.

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 21984427 - 2²³ = 13595819 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21984421) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8074 + ... + 10447.

It is an arithmetic number, because the mean of its divisors is an integer number (5501034).

Almost surely, 2^21984427 is an apocalyptic number.

21984427 is a deficient number, since it is larger than the sum of its proper divisors (19709).

21984427 is a wasteful number, since it uses less digits than its factorization.

21984427 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19708.

The product of its digits is 32256, while the sum is 37.

The square root of 21984427 is about 4688.7553785626. The cubic root of 21984427 is about 280.1378020675.

The spelling of 21984427 in words is "twenty-one million, nine hundred eighty-four thousand, four hundred twenty-seven".