666642577 has 4 divisors (see below), whose sum is σ = 667627956. Its totient is φ = 665657200.

The previous prime is 666642553. The next prime is 666642589. The reversal of 666642577 is 775246666.

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

It can be written as a sum of positive squares in 2 ways, for example, as 594579456 + 72063121 = 24384^2 + 8489^2 .

It is a cyclic number.

It is not a de Polignac number, because 666642577 - 2¹⁵ = 666609809 is a prime.

It is a Smith number, since the sum of its digits (49) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 666642577.

It is not an unprimeable number, because it can be changed into a prime (666642077) 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, 491674 + ... + 493027.

It is an arithmetic number, because the mean of its divisors is an integer number (166906989).

Almost surely, 2^666642577 is an apocalyptic number.

It is an amenable number.

666642577 is a deficient number, since it is larger than the sum of its proper divisors (985379).

666642577 is an equidigital number, since it uses as much as digits as its factorization.

666642577 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 985378.

The product of its digits is 2540160, while the sum is 49.

The square root of 666642577 is about 25819.4224761128. The cubic root of 666642577 is about 873.5699424785.

The spelling of 666642577 in words is "six hundred sixty-six million, six hundred forty-two thousand, five hundred seventy-seven".