665616601 has 4 divisors (see below), whose sum is σ = 716817892. Its totient is φ = 614415312.

The previous prime is 665616547. The next prime is 665616647. The reversal of 665616601 is 106616566.

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

It can be written as a sum of positive squares in 2 ways, for example, as 210221001 + 455395600 = 14499^2 + 21340^2 .

It is a cyclic number.

It is not a de Polignac number, because 665616601 - 2⁹ = 665616089 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665616661) 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, 25600626 + ... + 25600651.

It is an arithmetic number, because the mean of its divisors is an integer number (179204473).

Almost surely, 2^665616601 is an apocalyptic number.

It is an amenable number.

665616601 is a deficient number, since it is larger than the sum of its proper divisors (51201291).

665616601 is a wasteful number, since it uses less digits than its factorization.

665616601 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51201290.

The product of its (nonzero) digits is 38880, while the sum is 37.

The square root of 665616601 is about 25799.5465270225. The cubic root of 665616601 is about 873.1215652881.

The spelling of 665616601 in words is "six hundred sixty-five million, six hundred sixteen thousand, six hundred one".