665013409 has 2 divisors, whose sum is σ = 665013410. Its totient is φ = 665013408.

The previous prime is 665013407. The next prime is 665013439. The reversal of 665013409 is 904310566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 535691025 + 129322384 = 23145^2 + 11372^2 .

It is a cyclic number.

It is not a de Polignac number, because 665013409 - 2¹ = 665013407 is a prime.

Together with 665013407, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (665013403) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332506704 + 332506705.

It is an arithmetic number, because the mean of its divisors is an integer number (332506705).

Almost surely, 2^665013409 is an apocalyptic number.

It is an amenable number.

665013409 is a deficient number, since it is larger than the sum of its proper divisors (1).

665013409 is an equidigital number, since it uses as much as digits as its factorization.

665013409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 19440, while the sum is 34.

The square root of 665013409 is about 25787.8539045032. The cubic root of 665013409 is about 872.8577401813.

The spelling of 665013409 in words is "six hundred sixty-five million, thirteen thousand, four hundred nine".