1666138745 has 16 divisors (see below), whose sum is σ = 2092158720. Its totient is φ = 1271375424.

The previous prime is 1666138693. The next prime is 1666138757. The reversal of 1666138745 is 5478316661.

It is a cyclic number.

It is not a de Polignac number, because 1666138745 - 2⁸ = 1666138489 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1666138745.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 21107 + ... + 61463.

It is an arithmetic number, because the mean of its divisors is an integer number (130759920).

Almost surely, 2^1666138745 is an apocalyptic number.

It is an amenable number.

1666138745 is a deficient number, since it is larger than the sum of its proper divisors (426019975).

1666138745 is a wasteful number, since it uses less digits than its factorization.

1666138745 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40744.

The product of its digits is 725760, while the sum is 47.

The square root of 1666138745 is about 40818.3628407608. The cubic root of 1666138745 is about 1185.5059042075.

The spelling of 1666138745 in words is "one billion, six hundred sixty-six million, one hundred thirty-eight thousand, seven hundred forty-five".