1665665671 has 2 divisors, whose sum is σ = 1665665672. Its totient is φ = 1665665670.

The previous prime is 1665665657. The next prime is 1665665689. The reversal of 1665665671 is 1765665661.

It is a weak prime.

It is an emirp because it is prime and its reverse (1765665661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1665665671 - 2¹³ = 1665657479 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1665665641) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 832832835 + 832832836.

It is an arithmetic number, because the mean of its divisors is an integer number (832832836).

Almost surely, 2^1665665671 is an apocalyptic number.

1665665671 is a deficient number, since it is larger than the sum of its proper divisors (1).

1665665671 is an equidigital number, since it uses as much as digits as its factorization.

1665665671 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1360800, while the sum is 49.

The square root of 1665665671 is about 40812.5675619655. The cubic root of 1665665671 is about 1185.3936916421.

The spelling of 1665665671 in words is "one billion, six hundred sixty-five million, six hundred sixty-five thousand, six hundred seventy-one".