1666878720 has 144 divisors (see below), whose sum is σ = 5733272832. Its totient is φ = 410296320.

The previous prime is 1666878691. The next prime is 1666878737. The reversal of 1666878720 is 278786661.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 33225 + ... + 66615.

Almost surely, 2^1666878720 is an apocalyptic number.

1666878720 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1666878720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2866636416).

1666878720 is an abundant number, since it is smaller than the sum of its proper divisors (4066394112).

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

1666878720 is a wasteful number, since it uses less digits than its factorization.

1666878720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 33428 (or 33414 counting only the distinct ones).

The product of its (nonzero) digits is 1354752, while the sum is 51.

The square root of 1666878720 is about 40827.4260761072. The cubic root of 1666878720 is about 1185.6813827697.

The spelling of 1666878720 in words is "one billion, six hundred sixty-six million, eight hundred seventy-eight thousand, seven hundred twenty".