665699 has 4 divisors (see below), whose sum is σ = 667464. Its totient is φ = 663936.

The previous prime is 665677. The next prime is 665713. The reversal of 665699 is 996566.

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

It is a cyclic number.

It is not a de Polignac number, because 665699 - 2¹² = 661603 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665629) 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, 62 + ... + 1155.

It is an arithmetic number, because the mean of its divisors is an integer number (166866).

2⁶⁶⁵⁶⁹⁹ is an apocalyptic number.

665699 is a deficient number, since it is larger than the sum of its proper divisors (1765).

665699 is a wasteful number, since it uses less digits than its factorization.

665699 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1764.

The product of its digits is 87480, while the sum is 41.

The square root of 665699 is about 815.9037933482. The cubic root of 665699 is about 87.3157592722.

The spelling of 665699 in words is "six hundred sixty-five thousand, six hundred ninety-nine".