1666820684 has 24 divisors (see below), whose sum is σ = 2973768000. Its totient is φ = 817315200.

The previous prime is 1666820677. The next prime is 1666820689. The reversal of 1666820684 is 4860286661.

It is a happy number.

It is a super-2 number, since 2×1666820684² = 5556582385220455712, which contains 22 as substring.

It is a Smith number, since the sum of its digits (47) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (1666820689) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 29384 + ... + 64784.

It is an arithmetic number, because the mean of its divisors is an integer number (123907000).

Almost surely, 2^1666820684 is an apocalyptic number.

It is an amenable number.

1666820684 is a deficient number, since it is larger than the sum of its proper divisors (1306947316).

1666820684 is a wasteful number, since it uses less digits than its factorization.

1666820684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 35633 (or 35631 counting only the distinct ones).

The product of its (nonzero) digits is 663552, while the sum is 47.

The square root of 1666820684 is about 40826.7153222005. The cubic root of 1666820684 is about 1185.6676219199.

The spelling of 1666820684 in words is "one billion, six hundred sixty-six million, eight hundred twenty thousand, six hundred eighty-four".