666255747633721 has 4 divisors (see below), whose sum is σ = 761435140152832. Its totient is φ = 571076355114612.

The previous prime is 666255747633691. The next prime is 666255747633727. The reversal of 666255747633721 is 127336747552666.

666255747633721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 666255747633721 - 2⁹ = 666255747633209 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (666255747633727) 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, 47589696259545 + ... + 47589696259558.

It is an arithmetic number, because the mean of its divisors is an integer number (190358785038208).

Almost surely, 2^{666255747633721} is an apocalyptic number.

It is an amenable number.

666255747633721 is a deficient number, since it is larger than the sum of its proper divisors (95179392519111).

666255747633721 is an equidigital number, since it uses as much as digits as its factorization.

666255747633721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 95179392519110.

The product of its digits is 1600300800, while the sum is 70.

The spelling of 666255747633721 in words is "six hundred sixty-six trillion, two hundred fifty-five billion, seven hundred forty-seven million, six hundred thirty-three thousand, seven hundred twenty-one".