21021166 has 8 divisors (see below), whose sum is σ = 31690800. Its totient is φ = 10457568.

The previous prime is 21021157. The next prime is 21021181. The reversal of 21021166 is 66112012.

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

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 26011 + ... + 26806.

It is an arithmetic number, because the mean of its divisors is an integer number (3961350).

Almost surely, 2^21021166 is an apocalyptic number.

21021166 is a deficient number, since it is larger than the sum of its proper divisors (10669634).

21021166 is a wasteful number, since it uses less digits than its factorization.

21021166 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53018.

The product of its (nonzero) digits is 144, while the sum is 19.

The square root of 21021166 is about 4584.8845132675. The cubic root of 21021166 is about 275.9850776081.

Adding to 21021166 its reverse (66112012), we get a palindrome (87133178).

The spelling of 21021166 in words is "twenty-one million, twenty-one thousand, one hundred sixty-six".