21016117 has 4 divisors (see below), whose sum is σ = 21232876. Its totient is φ = 20799360.

The previous prime is 21016103. The next prime is 21016123. The reversal of 21016117 is 71161012.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 12773476 + 8242641 = 3574^2 + 2871^2 .

It is a cyclic number.

It is not a de Polignac number, because 21016117 - 2¹¹ = 21014069 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21016094 and 21016103.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21016187) by changing a digit.

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, 108234 + ... + 108427.

It is an arithmetic number, because the mean of its divisors is an integer number (5308219).

Almost surely, 2^21016117 is an apocalyptic number.

It is an amenable number.

21016117 is a deficient number, since it is larger than the sum of its proper divisors (216759).

21016117 is an equidigital number, since it uses as much as digits as its factorization.

21016117 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 216758.

The product of its (nonzero) digits is 84, while the sum is 19.

The square root of 21016117 is about 4584.3338665503. Note that the first 3 decimals coincide. The cubic root of 21016117 is about 275.9629798768.

Adding to 21016117 its reverse (71161012), we get a palindrome (92177129).

The spelling of 21016117 in words is "twenty-one million, sixteen thousand, one hundred seventeen".