21170216 has 24 divisors (see below), whose sum is σ = 40817070. Its totient is φ = 10293696.

The previous prime is 21170213. The next prime is 21170221. The reversal of 21170216 is 61207112.

It can be written as a sum of positive squares in 3 ways, for example, as 20666116 + 504100 = 4546^2 + 710^2 .

It is not an unprimeable number, because it can be changed into a prime (21170213) 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 5 ways as a sum of consecutive naturals, for example, 9986 + ... + 11918.

Almost surely, 2^21170216 is an apocalyptic number.

It is an amenable number.

21170216 is a deficient number, since it is larger than the sum of its proper divisors (19646854).

21170216 is a wasteful number, since it uses less digits than its factorization.

21170216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2013 (or 1972 counting only the distinct ones).

The product of its (nonzero) digits is 168, while the sum is 20.

The square root of 21170216 is about 4601.1103007861. The cubic root of 21170216 is about 276.6358301788.

Adding to 21170216 its reverse (61207112), we get a palindrome (82377328).

It can be divided in two parts, 2 and 1170216, that multiplied together give a palindrome (2340432).

The spelling of 21170216 in words is "twenty-one million, one hundred seventy thousand, two hundred sixteen".