665025409 has 2 divisors, whose sum is σ = 665025410. Its totient is φ = 665025408.

The previous prime is 665025391. The next prime is 665025421. The reversal of 665025409 is 904520566.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 626000400 + 39025009 = 25020^2 + 6247^2 .

It is a cyclic number.

It is not a de Polignac number, because 665025409 - 2¹¹ = 665023361 is a prime.

It is not a weakly prime, because it can be changed into another prime (665025469) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332512704 + 332512705.

It is an arithmetic number, because the mean of its divisors is an integer number (332512705).

Almost surely, 2^665025409 is an apocalyptic number.

It is an amenable number.

665025409 is a deficient number, since it is larger than the sum of its proper divisors (1).

665025409 is an equidigital number, since it uses as much as digits as its factorization.

665025409 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64800, while the sum is 37.

The square root of 665025409 is about 25788.0865711281. The cubic root of 665025409 is about 872.8629903160.

The spelling of 665025409 in words is "six hundred sixty-five million, twenty-five thousand, four hundred nine".