661716511171 has 2 divisors, whose sum is σ = 661716511172. Its totient is φ = 661716511170.

The previous prime is 661716511129. The next prime is 661716511193. The reversal of 661716511171 is 171115617166.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661716511171 - 2¹¹ = 661716509123 is a prime.

It is not a weakly prime, because it can be changed into another prime (661716511121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330858255585 + 330858255586.

It is an arithmetic number, because the mean of its divisors is an integer number (330858255586).

Almost surely, 2^661716511171 is an apocalyptic number.

661716511171 is a deficient number, since it is larger than the sum of its proper divisors (1).

661716511171 is an equidigital number, since it uses as much as digits as its factorization.

661716511171 is an evil number, because the sum of its binary digits is even.

The product of its digits is 52920, while the sum is 43.

The spelling of 661716511171 in words is "six hundred sixty-one billion, seven hundred sixteen million, five hundred eleven thousand, one hundred seventy-one".