217561165651 has 2 divisors, whose sum is σ = 217561165652. Its totient is φ = 217561165650.

The previous prime is 217561165579. The next prime is 217561165663. The reversal of 217561165651 is 156561165712.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 217561165651 - 2³³ = 208971231059 is a prime.

It is not a weakly prime, because it can be changed into another prime (217561160651) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 108780582825 + 108780582826.

It is an arithmetic number, because the mean of its divisors is an integer number (108780582826).

Almost surely, 2^217561165651 is an apocalyptic number.

217561165651 is a deficient number, since it is larger than the sum of its proper divisors (1).

217561165651 is an equidigital number, since it uses as much as digits as its factorization.

217561165651 is an evil number, because the sum of its binary digits is even.

The product of its digits is 378000, while the sum is 46.

The spelling of 217561165651 in words is "two hundred seventeen billion, five hundred sixty-one million, one hundred sixty-five thousand, six hundred fifty-one".