665445557 has 4 divisors (see below), whose sum is σ = 760509216. Its totient is φ = 570381900.

The previous prime is 665445551. The next prime is 665445559. The reversal of 665445557 is 755544566.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 665445557 - 2¹⁸ = 665183413 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665445551) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 47531819 + ... + 47531832.

It is an arithmetic number, because the mean of its divisors is an integer number (190127304).

Almost surely, 2^665445557 is an apocalyptic number.

It is an amenable number.

665445557 is a deficient number, since it is larger than the sum of its proper divisors (95063659).

665445557 is an equidigital number, since it uses as much as digits as its factorization.

665445557 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95063658.

The product of its digits is 2520000, while the sum is 47.

The square root of 665445557 is about 25796.2314495742. The cubic root of 665445557 is about 873.0467699786.

Subtracting 665445557 from its reverse (755544566), we obtain a palindrome (90099009).

The spelling of 665445557 in words is "six hundred sixty-five million, four hundred forty-five thousand, five hundred fifty-seven".