665611070221 has 4 divisors (see below), whose sum is σ = 669329568000. Its totient is φ = 661892572444.

The previous prime is 665611070197. The next prime is 665611070233. The reversal of 665611070221 is 122070116566.

It is a happy number.

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 665611070221 - 2⁹ = 665611069709 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 (665611070021) 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, 1859248621 + ... + 1859248978.

It is an arithmetic number, because the mean of its divisors is an integer number (167332392000).

Almost surely, 2^665611070221 is an apocalyptic number.

It is an amenable number.

665611070221 is a deficient number, since it is larger than the sum of its proper divisors (3718497779).

665611070221 is a wasteful number, since it uses less digits than its factorization.

665611070221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3718497778.

The product of its (nonzero) digits is 30240, while the sum is 37.

Adding to 665611070221 its reverse (122070116566), we get a palindrome (787681186787).

The spelling of 665611070221 in words is "six hundred sixty-five billion, six hundred eleven million, seventy thousand, two hundred twenty-one".