1666403680 has 24 divisors (see below), whose sum is σ = 3936879072. Its totient is φ = 666561408.

The previous prime is 1666403671. The next prime is 1666403701. The reversal of 1666403680 is 863046661.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5207352 + ... + 5207671.

It is an arithmetic number, because the mean of its divisors is an integer number (164036628).

Almost surely, 2^1666403680 is an apocalyptic number.

1666403680 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1666403680 is an abundant number, since it is smaller than the sum of its proper divisors (2270475392).

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

1666403680 is a wasteful number, since it uses less digits than its factorization.

1666403680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10415038 (or 10415030 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 40.

The square root of 1666403680 is about 40821.6080036051. The cubic root of 1666403680 is about 1185.5687371821.

The spelling of 1666403680 in words is "one billion, six hundred sixty-six million, four hundred three thousand, six hundred eighty".