3891666816 has 128 divisors (see below), whose sum is σ = 11625062400. Its totient is φ = 1281498624.

The previous prime is 3891666767. The next prime is 3891666841. The reversal of 3891666816 is 6186661983.

It is a tau number, because it is divible by the number of its divisors (128).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a nude number because it is divisible by every one of its digits.

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, 280065 + ... + 293631.

It is an arithmetic number, because the mean of its divisors is an integer number (90820800).

Almost surely, 2^3891666816 is an apocalyptic number.

3891666816 is a gapful number since it is divisible by the number (36) 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 3891666816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (5812531200).

3891666816 is an abundant number, since it is smaller than the sum of its proper divisors (7733395584).

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

3891666816 is a wasteful number, since it uses less digits than its factorization.

3891666816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13673 (or 13655 counting only the distinct ones).

The product of its digits is 2239488, while the sum is 54.

The square root of 3891666816 is about 62383.2254376126. The cubic root of 3891666816 is about 1572.9390112696.

The spelling of 3891666816 in words is "three billion, eight hundred ninety-one million, six hundred sixty-six thousand, eight hundred sixteen".