666541597 has 4 divisors (see below), whose sum is σ = 689525820. Its totient is φ = 643557376.

The previous prime is 666541583. The next prime is 666541607. The reversal of 666541597 is 795145666.

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 195608196 + 470933401 = 13986^2 + 21701^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-666541597 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 666541597.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666541507) 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, 11492068 + ... + 11492125.

It is an arithmetic number, because the mean of its divisors is an integer number (172381455).

Almost surely, 2^666541597 is an apocalyptic number.

It is an amenable number.

666541597 is a deficient number, since it is larger than the sum of its proper divisors (22984223).

666541597 is a wasteful number, since it uses less digits than its factorization.

666541597 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22984222.

The product of its digits is 1360800, while the sum is 49.

The square root of 666541597 is about 25817.4668974321. The cubic root of 666541597 is about 873.5258321109.

The spelling of 666541597 in words is "six hundred sixty-six million, five hundred forty-one thousand, five hundred ninety-seven".