1665945856 has 27 divisors (see below), whose sum is σ = 3326688183. Its totient is φ = 832646400.

The previous prime is 1665945851. The next prime is 1665945887. The reversal of 1665945856 is 6585495661.

The square root of 1665945856 is 40816.

It is a perfect power (a square), and thus also a powerful number.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 1665945797 and 1665945806.

It is not an unprimeable number, because it can be changed into a prime (1665945851) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 651781 + ... + 654331.

Almost surely, 2^1665945856 is an apocalyptic number.

1665945856 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

1665945856 is the 40816-th square number.

It is an amenable number.

1665945856 is a deficient number, since it is larger than the sum of its proper divisors (1660742327).

1665945856 is an frugal number, since it uses more digits than its factorization.

1665945856 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5118 (or 2553 counting only the distinct ones).

The product of its digits is 7776000, while the sum is 55.

The cubic root of 1665945856 is about 1185.4601537412.

The spelling of 1665945856 in words is "one billion, six hundred sixty-five million, nine hundred forty-five thousand, eight hundred fifty-six".