21986171 has 4 divisors (see below), whose sum is σ = 22146792. Its totient is φ = 21825552.

The previous prime is 21986143. The next prime is 21986191. The reversal of 21986171 is 17168912.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21986171 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21986101) 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, 80105 + ... + 80378.

It is an arithmetic number, because the mean of its divisors is an integer number (5536698).

Almost surely, 2^21986171 is an apocalyptic number.

21986171 is a deficient number, since it is larger than the sum of its proper divisors (160621).

21986171 is a wasteful number, since it uses less digits than its factorization.

21986171 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 160620.

The product of its digits is 6048, while the sum is 35.

The square root of 21986171 is about 4688.9413517339. The cubic root of 21986171 is about 280.1452095445.

The spelling of 21986171 in words is "twenty-one million, nine hundred eighty-six thousand, one hundred seventy-one".