21010216 has 8 divisors (see below), whose sum is σ = 39394170. Its totient is φ = 10505104.

The previous prime is 21010193. The next prime is 21010217. The reversal of 21010216 is 61201012.

It can be written as a sum of positive squares in only one way, i.e., 20884900 + 125316 = 4570^2 + 354^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a junction number, because it is equal to n+sod(n) for n = 21010196 and 21010205.

It is not an unprimeable number, because it can be changed into a prime (21010217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1313131 + ... + 1313146.

Almost surely, 2^21010216 is an apocalyptic number.

It is an amenable number.

21010216 is a deficient number, since it is larger than the sum of its proper divisors (18383954).

21010216 is a wasteful number, since it uses less digits than its factorization.

21010216 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2626283 (or 2626279 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 13.

The square root of 21010216 is about 4583.6902164086. The cubic root of 21010216 is about 275.9371487495.

Adding to 21010216 its reverse (61201012), we get a palindrome (82211228).

The spelling of 21010216 in words is "twenty-one million, ten thousand, two hundred sixteen".