21686143 has 8 divisors (see below), whose sum is σ = 22487040. Its totient is φ = 20891640.

The previous prime is 21686123. The next prime is 21686177. The reversal of 21686143 is 34168612.

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 21686143 - 2⁵ = 21686111 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (31).

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21686123) 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 7 ways as a sum of consecutive naturals, for example, 5946 + ... + 8872.

It is an arithmetic number, because the mean of its divisors is an integer number (2810880).

Almost surely, 2^21686143 is an apocalyptic number.

21686143 is a deficient number, since it is larger than the sum of its proper divisors (800897).

21686143 is a wasteful number, since it uses less digits than its factorization.

21686143 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3197.

The product of its digits is 6912, while the sum is 31.

The square root of 21686143 is about 4656.8383051165. The cubic root of 21686143 is about 278.8650615230.

The spelling of 21686143 in words is "twenty-one million, six hundred eighty-six thousand, one hundred forty-three".