1666686740 has 24 divisors (see below), whose sum is σ = 3574513152. Its totient is φ = 652489760.

The previous prime is 1666686739. The next prime is 1666686803. The reversal of 1666686740 is 476866661.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

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 7 ways as a sum of consecutive naturals, for example, 885596 + ... + 887475.

It is an arithmetic number, because the mean of its divisors is an integer number (148938048).

Almost surely, 2^1666686740 is an apocalyptic number.

1666686740 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1666686740 is an abundant number, since it is smaller than the sum of its proper divisors (1907826412).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1666686740 is a wasteful number, since it uses less digits than its factorization.

1666686740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1773127 (or 1773125 counting only the distinct ones).

The product of its (nonzero) digits is 1741824, while the sum is 50.

The square root of 1666686740 is about 40825.0748927666. The cubic root of 1666686740 is about 1185.6358613912.

The spelling of 1666686740 in words is "one billion, six hundred sixty-six million, six hundred eighty-six thousand, seven hundred forty".