1665918945 has 12 divisors (see below), whose sum is σ = 2887592916. Its totient is φ = 888490080.

The previous prime is 1665918941. The next prime is 1665918959. The reversal of 1665918945 is 5498195661.

1665918945 is a `hidden beast` number, since 1 + 6 + 6 + 591 + 8 + 9 + 45 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 1220244624 + 445674321 = 34932^2 + 21111^2 .

It is not a de Polignac number, because 1665918945 - 2² = 1665918941 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 1665918891 and 1665918900.

It is not an unprimeable number, because it can be changed into a prime (1665918941) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 18510166 + ... + 18510255.

It is an arithmetic number, because the mean of its divisors is an integer number (240632743).

Almost surely, 2^1665918945 is an apocalyptic number.

1665918945 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1665918945 is a deficient number, since it is larger than the sum of its proper divisors (1221673971).

1665918945 is a wasteful number, since it uses less digits than its factorization.

1665918945 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 37020432 (or 37020429 counting only the distinct ones).

The product of its digits is 2332800, while the sum is 54.

The square root of 1665918945 is about 40815.6703362814. The cubic root of 1665918945 is about 1185.4537705626.

The spelling of 1665918945 in words is "one billion, six hundred sixty-five million, nine hundred eighteen thousand, nine hundred forty-five".