21016161 has 12 divisors (see below), whose sum is σ = 30414592. Its totient is φ = 13984056.

The previous prime is 21016159. The next prime is 21016187. The reversal of 21016161 is 16161012.

It is not a de Polignac number, because 21016161 - 2¹ = 21016159 is a prime.

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

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21012161) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3540 + ... + 7386.

Almost surely, 2^21016161 is an apocalyptic number.

It is an amenable number.

21016161 is a deficient number, since it is larger than the sum of its proper divisors (9398431).

21016161 is a wasteful number, since it uses less digits than its factorization.

21016161 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4460 (or 4457 counting only the distinct ones).

The product of its (nonzero) digits is 72, while the sum is 18.

The square root of 21016161 is about 4584.3386655002. The cubic root of 21016161 is about 275.9631724649.

Adding to 21016161 its reverse (16161012), we get a palindrome (37177173).

The spelling of 21016161 in words is "twenty-one million, sixteen thousand, one hundred sixty-one".