666561572057 has 4 divisors (see below), whose sum is σ = 701643760080. Its totient is φ = 631479384036.

The previous prime is 666561572023. The next prime is 666561572069. The reversal of 666561572057 is 750275165666.

666561572057 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 666561572057 - 2²² = 666557377753 is a prime.

It is a super-2 number, since 2×666561572057² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 666561571993 and 666561572011.

It is not an unprimeable number, because it can be changed into a prime (666561572557) 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, 17541093983 + ... + 17541094020.

It is an arithmetic number, because the mean of its divisors is an integer number (175410940020).

Almost surely, 2^666561572057 is an apocalyptic number.

It is an amenable number.

666561572057 is a deficient number, since it is larger than the sum of its proper divisors (35082188023).

666561572057 is a wasteful number, since it uses less digits than its factorization.

666561572057 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 35082188022.

The product of its (nonzero) digits is 15876000, while the sum is 56.

The spelling of 666561572057 in words is "six hundred sixty-six billion, five hundred sixty-one million, five hundred seventy-two thousand, fifty-seven".