661543171 has 2 divisors, whose sum is σ = 661543172. Its totient is φ = 661543170.

The previous prime is 661543123. The next prime is 661543217. The reversal of 661543171 is 171345166.

661543171 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661543171 - 2¹⁷ = 661412099 is a prime.

It is not a weakly prime, because it can be changed into another prime (661583171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330771585 + 330771586.

It is an arithmetic number, because the mean of its divisors is an integer number (330771586).

Almost surely, 2^661543171 is an apocalyptic number.

661543171 is a deficient number, since it is larger than the sum of its proper divisors (1).

661543171 is an equidigital number, since it uses as much as digits as its factorization.

661543171 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 15120, while the sum is 34.

The square root of 661543171 is about 25720.4815468140. The cubic root of 661543171 is about 871.3368143531.

The spelling of 661543171 in words is "six hundred sixty-one million, five hundred forty-three thousand, one hundred seventy-one".