21288166 has 8 divisors (see below), whose sum is σ = 31982544. Its totient is φ = 10627320.

The previous prime is 21288161. The next prime is 21288167. The reversal of 21288166 is 66188212.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21288161) 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, 6730 + ... + 9373.

It is an arithmetic number, because the mean of its divisors is an integer number (3997818).

Almost surely, 2^21288166 is an apocalyptic number.

21288166 is a deficient number, since it is larger than the sum of its proper divisors (10694378).

21288166 is a wasteful number, since it uses less digits than its factorization.

21288166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16766.

The product of its digits is 9216, while the sum is 34.

The square root of 21288166 is about 4613.9100554736. The cubic root of 21288166 is about 277.1486384423.

The spelling of 21288166 in words is "twenty-one million, two hundred eighty-eight thousand, one hundred sixty-six".