1978666 has 8 divisors (see below), whose sum is σ = 2985120. Its totient is φ = 983628.

The previous prime is 1978663. The next prime is 1978673. The reversal of 1978666 is 6668791.

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

It is not an unprimeable number, because it can be changed into a prime (1978661) 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, 2406 + ... + 3121.

It is an arithmetic number, because the mean of its divisors is an integer number (373140).

2^1978666 is an apocalyptic number.

1978666 is a deficient number, since it is larger than the sum of its proper divisors (1006454).

1978666 is a wasteful number, since it uses less digits than its factorization.

1978666 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5708.

The product of its digits is 108864, while the sum is 43.

The square root of 1978666 is about 1406.6506318201. The cubic root of 1978666 is about 125.5425166656.

The spelling of 1978666 in words is "one million, nine hundred seventy-eight thousand, six hundred sixty-six".