216164021 has 2 divisors, whose sum is σ = 216164022. Its totient is φ = 216164020.

The previous prime is 216164009. The next prime is 216164071. The reversal of 216164021 is 120461612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 206640625 + 9523396 = 14375^2 + 3086^2 .

It is a cyclic number.

It is not a de Polignac number, because 216164021 - 2¹⁰ = 216162997 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216164071) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108082010 + 108082011.

It is an arithmetic number, because the mean of its divisors is an integer number (108082011).

Almost surely, 2^216164021 is an apocalyptic number.

It is an amenable number.

216164021 is a deficient number, since it is larger than the sum of its proper divisors (1).

216164021 is an equidigital number, since it uses as much as digits as its factorization.

216164021 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 216164021 is about 14702.5175055158. The cubic root of 216164021 is about 600.1518328710.

The spelling of 216164021 in words is "two hundred sixteen million, one hundred sixty-four thousand, twenty-one".