1665938816 has 64 divisors (see below), whose sum is σ = 3378276720. Its totient is φ = 818184192.

The previous prime is 1665938803. The next prime is 1665938831. The reversal of 1665938816 is 6188395661.

It is a tau number, because it is divible by the number of its divisors (64).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2475056 + ... + 2475728.

Almost surely, 2^1665938816 is an apocalyptic number.

1665938816 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 1665938816, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1689138360).

1665938816 is an abundant number, since it is smaller than the sum of its proper divisors (1712337904).

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

1665938816 is an equidigital number, since it uses as much as digits as its factorization.

1665938816 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1003 (or 991 counting only the distinct ones).

The product of its digits is 1866240, while the sum is 53.

The square root of 1665938816 is about 40815.9137592190. The cubic root of 1665938816 is about 1185.4584838888.

The spelling of 1665938816 in words is "one billion, six hundred sixty-five million, nine hundred thirty-eight thousand, eight hundred sixteen".