1666819800 has 144 divisors (see below), whose sum is σ = 5619625440. Its totient is φ = 442748160.

The previous prime is 1666819753. The next prime is 1666819801. The reversal of 1666819800 is 89186661.

It is a happy number.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1666819801) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 496929 + ... + 500271.

Almost surely, 2^1666819800 is an apocalyptic number.

1666819800 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 1666819800, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2809812720).

1666819800 is an abundant number, since it is smaller than the sum of its proper divisors (3952805640).

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

1666819800 is a wasteful number, since it uses less digits than its factorization.

1666819800 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3642 (or 3630 counting only the distinct ones).

The product of its (nonzero) digits is 124416, while the sum is 45.

The square root of 1666819800 is about 40826.7044959546. The cubic root of 1666819800 is about 1185.6674123132.

The spelling of 1666819800 in words is "one billion, six hundred sixty-six million, eight hundred nineteen thousand, eight hundred".