1666437109 has 2 divisors, whose sum is σ = 1666437110. Its totient is φ = 1666437108.

The previous prime is 1666437107. The next prime is 1666437131. The reversal of 1666437109 is 9017346661.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1119906225 + 546530884 = 33465^2 + 23378^2 .

It is an emirp because it is prime and its reverse (9017346661) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1666437109 - 2¹ = 1666437107 is a prime.

Together with 1666437107, it forms a pair of twin primes.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1666437107) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 833218554 + 833218555.

It is an arithmetic number, because the mean of its divisors is an integer number (833218555).

Almost surely, 2^1666437109 is an apocalyptic number.

It is an amenable number.

1666437109 is a deficient number, since it is larger than the sum of its proper divisors (1).

1666437109 is an equidigital number, since it uses as much as digits as its factorization.

1666437109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 163296, while the sum is 43.

The square root of 1666437109 is about 40822.0174538202. The cubic root of 1666437109 is about 1185.5766648555.

The spelling of 1666437109 in words is "one billion, six hundred sixty-six million, four hundred thirty-seven thousand, one hundred nine".