21213166 has 8 divisors (see below), whose sum is σ = 34267464. Its totient is φ = 9790680.

The previous prime is 21213163. The next prime is 21213187. The reversal of 21213166 is 66131212.

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 (21213163) 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, 407920 + ... + 407971.

It is an arithmetic number, because the mean of its divisors is an integer number (4283433).

Almost surely, 2^21213166 is an apocalyptic number.

21213166 is a gapful number since it is divisible by the number (26) formed by its first and last digit.

21213166 is a deficient number, since it is larger than the sum of its proper divisors (13054298).

21213166 is a wasteful number, since it uses less digits than its factorization.

21213166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 815906.

The product of its digits is 432, while the sum is 22.

The square root of 21213166 is about 4605.7752876145. The cubic root of 21213166 is about 276.8227828124.

Adding to 21213166 its reverse (66131212), we get a palindrome (87344378).

The spelling of 21213166 in words is "twenty-one million, two hundred thirteen thousand, one hundred sixty-six".