665525566 has 4 divisors (see below), whose sum is σ = 998288352. Its totient is φ = 332762782.

The previous prime is 665525519. The next prime is 665525569.

665525566 is nontrivially palindromic in base 10.

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (665525569) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 166381390 + ... + 166381393.

It is an arithmetic number, because the mean of its divisors is an integer number (249572088).

Almost surely, 2^665525566 is an apocalyptic number.

665525566 is a deficient number, since it is larger than the sum of its proper divisors (332762786).

665525566 is a wasteful number, since it uses less digits than its factorization.

665525566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 332762785.

The product of its digits is 1620000, while the sum is 46.

The square root of 665525566 is about 25797.7821914986. The cubic root of 665525566 is about 873.0817584656.

The spelling of 665525566 in words is "six hundred sixty-five million, five hundred twenty-five thousand, five hundred sixty-six".