216021517 has 2 divisors, whose sum is σ = 216021518. Its totient is φ = 216021516.

The previous prime is 216021511. The next prime is 216021521. The reversal of 216021517 is 715120612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 185340996 + 30680521 = 13614^2 + 5539^2 .

It is a cyclic number.

It is not a de Polignac number, because 216021517 - 2⁷ = 216021389 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 216021491 and 216021500.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216021511) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108010758 + 108010759.

It is an arithmetic number, because the mean of its divisors is an integer number (108010759).

Almost surely, 2^216021517 is an apocalyptic number.

It is an amenable number.

216021517 is a deficient number, since it is larger than the sum of its proper divisors (1).

216021517 is an equidigital number, since it uses as much as digits as its factorization.

216021517 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 840, while the sum is 25.

The square root of 216021517 is about 14697.6704616752. The cubic root of 216021517 is about 600.0199224866.

The spelling of 216021517 in words is "two hundred sixteen million, twenty-one thousand, five hundred seventeen".