21169218 has 64 divisors (see below), whose sum is σ = 50872320. Its totient is φ = 5745600.

The previous prime is 21169157. The next prime is 21169219. The reversal of 21169218 is 81296112.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21169219) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 92328 + ... + 92556.

It is an arithmetic number, because the mean of its divisors is an integer number (794880).

Almost surely, 2^21169218 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21169218, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (25436160).

21169218 is an abundant number, since it is smaller than the sum of its proper divisors (29703102).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21169218 is a wasteful number, since it uses less digits than its factorization.

21169218 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 343.

The product of its digits is 1728, while the sum is 30.

The square root of 21169218 is about 4601.0018474241. The cubic root of 21169218 is about 276.6314830826.

The spelling of 21169218 in words is "twenty-one million, one hundred sixty-nine thousand, two hundred eighteen".