216840061 has 2 divisors, whose sum is σ = 216840062. Its totient is φ = 216840060.

The previous prime is 216840023. The next prime is 216840121. The reversal of 216840061 is 160048612.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 180768025 + 36072036 = 13445^2 + 6006^2 .

It is a cyclic number.

It is not a de Polignac number, because 216840061 - 2²⁵ = 183285629 is a prime.

It is a super-2 number, since 2×216840061² = 94039224108967442, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216840011) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108420030 + 108420031.

It is an arithmetic number, because the mean of its divisors is an integer number (108420031).

Almost surely, 2^216840061 is an apocalyptic number.

It is an amenable number.

216840061 is a deficient number, since it is larger than the sum of its proper divisors (1).

216840061 is an equidigital number, since it uses as much as digits as its factorization.

216840061 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2304, while the sum is 28.

The square root of 216840061 is about 14725.4901785985. The cubic root of 216840061 is about 600.7768280555.

Adding to 216840061 its reverse (160048612), we get a palindrome (376888673).

The spelling of 216840061 in words is "two hundred sixteen million, eight hundred forty thousand, sixty-one".