1800665856 has 216 divisors, whose sum is σ = 5855692080. Its totient is φ = 545402880.

The previous prime is 1800665851. The next prime is 1800665869. The reversal of 1800665856 is 6585660081.

1800665856 is a `hidden beast` number, since 1 + 8 + 0 + 0 + 66 + 585 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (216).

It is not an unprimeable number, because it can be changed into a prime (1800665851) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 835276 + ... + 837428.

Almost surely, 2^1800665856 is an apocalyptic number.

1800665856 is a gapful number since it is divisible by the number (16) 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 1800665856, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2927846040).

1800665856 is an abundant number, since it is smaller than the sum of its proper divisors (4055026224).

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

1800665856 is a wasteful number, since it uses less digits than its factorization.

1800665856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2200 (or 2169 counting only the distinct ones).

The product of its (nonzero) digits is 345600, while the sum is 45.

The square root of 1800665856 is about 42434.2533338340. The cubic root of 1800665856 is about 1216.5903758339.

The spelling of 1800665856 in words is "one billion, eight hundred million, six hundred sixty-five thousand, eight hundred fifty-six".