1666378894 has 8 divisors (see below), whose sum is σ = 2508464448. Its totient is φ = 830224080.

The previous prime is 1666378891. The next prime is 1666378921. The reversal of 1666378894 is 4988736661.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666378891) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1481982 + ... + 1483105.

It is an arithmetic number, because the mean of its divisors is an integer number (313558056).

Almost surely, 2^1666378894 is an apocalyptic number.

1666378894 is a deficient number, since it is larger than the sum of its proper divisors (842085554).

1666378894 is a wasteful number, since it uses less digits than its factorization.

1666378894 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2965370.

The product of its digits is 10450944, while the sum is 58.

The square root of 1666378894 is about 40821.3044132595. The cubic root of 1666378894 is about 1185.5628591241.

The spelling of 1666378894 in words is "one billion, six hundred sixty-six million, three hundred seventy-eight thousand, eight hundred ninety-four".