666605509951 has 4 divisors (see below), whose sum is σ = 666705592504. Its totient is φ = 666505427400.

The previous prime is 666605509939. The next prime is 666605509961. The reversal of 666605509951 is 159905506666.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 666605509951 - 2²⁹ = 666068639039 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 (666605509961) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 50031285 + ... + 50044606.

It is an arithmetic number, because the mean of its divisors is an integer number (166676398126).

Almost surely, 2^666605509951 is an apocalyptic number.

666605509951 is a deficient number, since it is larger than the sum of its proper divisors (100082553).

666605509951 is a wasteful number, since it uses less digits than its factorization.

666605509951 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 100082552.

The product of its (nonzero) digits is 13122000, while the sum is 58.

The spelling of 666605509951 in words is "six hundred sixty-six billion, six hundred five million, five hundred nine thousand, nine hundred fifty-one".