665913851 has 4 divisors (see below), whose sum is σ = 705085272. Its totient is φ = 626742432.

The previous prime is 665913823. The next prime is 665913869. The reversal of 665913851 is 158319566.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-665913851 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665912851) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 19585685 + ... + 19585718.

It is an arithmetic number, because the mean of its divisors is an integer number (176271318).

Almost surely, 2^665913851 is an apocalyptic number.

665913851 is a deficient number, since it is larger than the sum of its proper divisors (39171421).

665913851 is a wasteful number, since it uses less digits than its factorization.

665913851 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39171420.

The product of its digits is 194400, while the sum is 44.

The square root of 665913851 is about 25805.3066441769. The cubic root of 665913851 is about 873.2515183572.

The spelling of 665913851 in words is "six hundred sixty-five million, nine hundred thirteen thousand, eight hundred fifty-one".