665209973 has 2 divisors, whose sum is σ = 665209974. Its totient is φ = 665209972.

The previous prime is 665209967. The next prime is 665209991. The reversal of 665209973 is 379902566.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 406707889 + 258502084 = 20167^2 + 16078^2 .

It is a cyclic number.

It is not a de Polignac number, because 665209973 - 2²² = 661015669 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (665209903) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 332604986 + 332604987.

It is an arithmetic number, because the mean of its divisors is an integer number (332604987).

Almost surely, 2^665209973 is an apocalyptic number.

It is an amenable number.

665209973 is a deficient number, since it is larger than the sum of its proper divisors (1).

665209973 is an equidigital number, since it uses as much as digits as its factorization.

665209973 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 612360, while the sum is 47.

The square root of 665209973 is about 25791.6647969843. The cubic root of 665209973 is about 872.9437311828.

The spelling of 665209973 in words is "six hundred sixty-five million, two hundred nine thousand, nine hundred seventy-three".