1665455985 has 20 divisors (see below), whose sum is σ = 2985484788. Its totient is φ = 888242976.

The previous prime is 1665455969. The next prime is 1665455989. The reversal of 1665455985 is 5895545661.

1665455985 is a `hidden beast` number, since 1 + 6 + 6 + 5 + 4 + 559 + 85 = 666.

It can be written as a sum of positive squares in 2 ways, for example, as 776402496 + 889053489 = 27864^2 + 29817^2 .

It is not a de Polignac number, because 1665455985 - 2⁴ = 1665455969 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (1665455989) by changing a digit.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 2055714 + ... + 2056523.

Almost surely, 2^1665455985 is an apocalyptic number.

1665455985 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

1665455985 is a deficient number, since it is larger than the sum of its proper divisors (1320028803).

1665455985 is an equidigital number, since it uses as much as digits as its factorization.

1665455985 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4112254 (or 4112245 counting only the distinct ones).

The product of its digits is 6480000, while the sum is 54.

The square root of 1665455985 is about 40809.9985910316. The cubic root of 1665455985 is about 1185.3439475875.

The spelling of 1665455985 in words is "one billion, six hundred sixty-five million, four hundred fifty-five thousand, nine hundred eighty-five".