1665640416 has 384 divisors, whose sum is σ = 5413588992. Its totient is φ = 442368000.

The previous prime is 1665640397. The next prime is 1665640469. The reversal of 1665640416 is 6140465661.

It is a happy number.

1665640416 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 22816956 + ... + 22817028.

It is an arithmetic number, because the mean of its divisors is an integer number (14097888).

Almost surely, 2^1665640416 is an apocalyptic number.

1665640416 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 1665640416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2706794496).

1665640416 is an abundant number, since it is smaller than the sum of its proper divisors (3747948576).

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

1665640416 is a wasteful number, since it uses less digits than its factorization.

1665640416 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 186 (or 178 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 39.

The square root of 1665640416 is about 40812.2581585484. The cubic root of 1665640416 is about 1185.3877005901.

The spelling of 1665640416 in words is "one billion, six hundred sixty-five million, six hundred forty thousand, four hundred sixteen".