665161639 has 4 divisors (see below), whose sum is σ = 665726040. Its totient is φ = 664597240.

The previous prime is 665161631. The next prime is 665161649. The reversal of 665161639 is 936161566.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 665161639 - 2³ = 665161631 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 665161595 and 665161604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665161631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 280429 + ... + 282790.

It is an arithmetic number, because the mean of its divisors is an integer number (166431510).

Almost surely, 2^665161639 is an apocalyptic number.

665161639 is a deficient number, since it is larger than the sum of its proper divisors (564401).

665161639 is a wasteful number, since it uses less digits than its factorization.

665161639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 564400.

The product of its digits is 174960, while the sum is 43.

The square root of 665161639 is about 25790.7277718175. The cubic root of 665161639 is about 872.9225880421.

The spelling of 665161639 in words is "six hundred sixty-five million, one hundred sixty-one thousand, six hundred thirty-nine".