1666165639 has 2 divisors, whose sum is σ = 1666165640. Its totient is φ = 1666165638.

The previous prime is 1666165637. The next prime is 1666165643. The reversal of 1666165639 is 9365616661.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1666165639 - 2¹ = 1666165637 is a prime.

It is a super-2 number, since 2×1666165639² = 5552215873168556642, which contains 22 as substring.

Together with 1666165637, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 1666165592 and 1666165601.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1666165637) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833082819 + 833082820.

It is an arithmetic number, because the mean of its divisors is an integer number (833082820).

Almost surely, 2^1666165639 is an apocalyptic number.

1666165639 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666165639 is an equidigital number, since it uses as much as digits as its factorization.

1666165639 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1049760, while the sum is 49.

The square root of 1666165639 is about 40818.6922744960. The cubic root of 1666165639 is about 1185.5122827927.

The spelling of 1666165639 in words is "one billion, six hundred sixty-six million, one hundred sixty-five thousand, six hundred thirty-nine".