21866197 has 8 divisors (see below), whose sum is σ = 22246200. Its totient is φ = 21489600.

The previous prime is 21866189. The next prime is 21866209. The reversal of 21866197 is 79166812.

It can be written as a sum of positive squares in 4 ways, for example, as 10850436 + 11015761 = 3294^2 + 3319^2 .

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 21866197 - 2³ = 21866189 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 (21866137) 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, 14323 + ... + 15775.

It is an arithmetic number, because the mean of its divisors is an integer number (2780775).

Almost surely, 2^21866197 is an apocalyptic number.

It is an amenable number.

21866197 is a deficient number, since it is larger than the sum of its proper divisors (380003).

21866197 is a wasteful number, since it uses less digits than its factorization.

21866197 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1703.

The product of its digits is 36288, while the sum is 40.

The square root of 21866197 is about 4676.1305584853. The cubic root of 21866197 is about 279.6347149868.

The spelling of 21866197 in words is "twenty-one million, eight hundred sixty-six thousand, one hundred ninety-seven".