21016165 has 8 divisors (see below), whose sum is σ = 26703000. Its totient is φ = 15823872.

The previous prime is 21016159. The next prime is 21016187. The reversal of 21016165 is 56161012.

It can be written as a sum of positive squares in 4 ways, for example, as 213444 + 20802721 = 462^2 + 4561^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21016165 - 2²¹ = 18919013 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 123540 + ... + 123709.

It is an arithmetic number, because the mean of its divisors is an integer number (3337875).

Almost surely, 2^21016165 is an apocalyptic number.

It is an amenable number.

21016165 is a deficient number, since it is larger than the sum of its proper divisors (5686835).

21016165 is a wasteful number, since it uses less digits than its factorization.

21016165 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 247271.

The product of its (nonzero) digits is 360, while the sum is 22.

The square root of 21016165 is about 4584.3391017681. The cubic root of 21016165 is about 275.9631899729.

Adding to 21016165 its reverse (56161012), we get a palindrome (77177177).

The spelling of 21016165 in words is "twenty-one million, sixteen thousand, one hundred sixty-five".