1666242365 has 4 divisors (see below), whose sum is σ = 1999490844. Its totient is φ = 1332993888.

The previous prime is 1666242359. The next prime is 1666242367. The reversal of 1666242365 is 5632426661.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5632426661 = 29 ⋅194221609.

It can be written as a sum of positive squares in 2 ways, for example, as 506295001 + 1159947364 = 22501^2 + 34058^2 .

It is a cyclic number.

It is not a de Polignac number, because 1666242365 - 2¹⁰ = 1666241341 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666242367) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 166624232 + ... + 166624241.

It is an arithmetic number, because the mean of its divisors is an integer number (499872711).

Almost surely, 2^1666242365 is an apocalyptic number.

It is an amenable number.

1666242365 is a deficient number, since it is larger than the sum of its proper divisors (333248479).

1666242365 is an equidigital number, since it uses as much as digits as its factorization.

1666242365 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 333248478.

The product of its digits is 311040, while the sum is 41.

The square root of 1666242365 is about 40819.6321027027. The cubic root of 1666242365 is about 1185.5304799069.

The spelling of 1666242365 in words is "one billion, six hundred sixty-six million, two hundred forty-two thousand, three hundred sixty-five".