1665705213 has 6 divisors (see below), whose sum is σ = 2406018654. Its totient is φ = 1110470136.

The previous prime is 1665705187. The next prime is 1665705229. The reversal of 1665705213 is 3125075661.

1665705213 is a `hidden beast` number, since 1 + 6 + 65 + 70 + 521 + 3 = 666.

1665705213 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 1041804729 + 623900484 = 32277^2 + 24978^2 .

It is not a de Polignac number, because 1665705213 - 2¹⁰ = 1665704189 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1665705913) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 92539170 + ... + 92539187.

It is an arithmetic number, because the mean of its divisors is an integer number (401003109).

Almost surely, 2^1665705213 is an apocalyptic number.

It is an amenable number.

1665705213 is a deficient number, since it is larger than the sum of its proper divisors (740313441).

1665705213 is a wasteful number, since it uses less digits than its factorization.

1665705213 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 185078363 (or 185078360 counting only the distinct ones).

The product of its (nonzero) digits is 37800, while the sum is 36.

The square root of 1665705213 is about 40813.0519932043. The cubic root of 1665705213 is about 1185.4030717691.

The spelling of 1665705213 in words is "one billion, six hundred sixty-five million, seven hundred five thousand, two hundred thirteen".