665717538 has 16 divisors (see below), whose sum is σ = 1333635840. Its totient is φ = 221539056.

The previous prime is 665717491. The next prime is 665717539. The reversal of 665717538 is 835717566.

It is not an unprimeable number, because it can be changed into a prime (665717539) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 87753 + ... + 95036.

It is an arithmetic number, because the mean of its divisors is an integer number (83352240).

Almost surely, 2^665717538 is an apocalyptic number.

665717538 is an abundant number, since it is smaller than the sum of its proper divisors (667918302).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

665717538 is a wasteful number, since it uses less digits than its factorization.

665717538 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 183401.

The product of its digits is 1058400, while the sum is 48.

The square root of 665717538 is about 25801.5026306609. The cubic root of 665717538 is about 873.1656977095.

The spelling of 665717538 in words is "six hundred sixty-five million, seven hundred seventeen thousand, five hundred thirty-eight".