216721907 has 2 divisors, whose sum is σ = 216721908. Its totient is φ = 216721906.

The previous prime is 216721877. The next prime is 216721943. The reversal of 216721907 is 709127612.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 216721907 - 2¹⁴ = 216705523 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (216721957) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108360953 + 108360954.

It is an arithmetic number, because the mean of its divisors is an integer number (108360954).

Almost surely, 2^216721907 is an apocalyptic number.

216721907 is a deficient number, since it is larger than the sum of its proper divisors (1).

216721907 is an equidigital number, since it uses as much as digits as its factorization.

216721907 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 10584, while the sum is 35.

The square root of 216721907 is about 14721.4777451178. The cubic root of 216721907 is about 600.6676891172.

The spelling of 216721907 in words is "two hundred sixteen million, seven hundred twenty-one thousand, nine hundred seven".