665561636237 has 2 divisors, whose sum is σ = 665561636238. Its totient is φ = 665561636236.

The previous prime is 665561636227. The next prime is 665561636323. The reversal of 665561636237 is 732636165566.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 606110517961 + 59451118276 = 778531^2 + 243826^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-665561636237 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (665561636227) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332780818118 + 332780818119.

It is an arithmetic number, because the mean of its divisors is an integer number (332780818119).

Almost surely, 2^665561636237 is an apocalyptic number.

It is an amenable number.

665561636237 is a deficient number, since it is larger than the sum of its proper divisors (1).

665561636237 is an equidigital number, since it uses as much as digits as its factorization.

665561636237 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24494400, while the sum is 56.

The spelling of 665561636237 in words is "six hundred sixty-five billion, five hundred sixty-one million, six hundred thirty-six thousand, two hundred thirty-seven".