21090166 has 16 divisors (see below), whose sum is σ = 33606144. Its totient is φ = 9892224.

The previous prime is 21090161. The next prime is 21090197. The reversal of 21090166 is 66109012.

It is a self number, because there is not a number n which added to its sum of digits gives 21090166.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21090161) 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, 11851 + ... + 13513.

It is an arithmetic number, because the mean of its divisors is an integer number (2100384).

Almost surely, 2^21090166 is an apocalyptic number.

21090166 is a deficient number, since it is larger than the sum of its proper divisors (12515978).

21090166 is a wasteful number, since it uses less digits than its factorization.

21090166 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2055.

The product of its (nonzero) digits is 648, while the sum is 25.

The square root of 21090166 is about 4592.4030746440. The cubic root of 21090166 is about 276.2867128374.

Adding to 21090166 its reverse (66109012), we get a palindrome (87199178).

The spelling of 21090166 in words is "twenty-one million, ninety thousand, one hundred sixty-six".