216304661 has 2 divisors, whose sum is σ = 216304662. Its totient is φ = 216304660.

The previous prime is 216304657. The next prime is 216304687. The reversal of 216304661 is 166403612.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 210424036 + 5880625 = 14506^2 + 2425^2 .

It is a cyclic number.

It is not a de Polignac number, because 216304661 - 2² = 216304657 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (216304601) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108152330 + 108152331.

It is an arithmetic number, because the mean of its divisors is an integer number (108152331).

Almost surely, 2^216304661 is an apocalyptic number.

It is an amenable number.

216304661 is a deficient number, since it is larger than the sum of its proper divisors (1).

216304661 is an equidigital number, since it uses as much as digits as its factorization.

216304661 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 29.

The square root of 216304661 is about 14707.2995821803. The cubic root of 216304661 is about 600.2819609944.

The spelling of 216304661 in words is "two hundred sixteen million, three hundred four thousand, six hundred sixty-one".