665756513 has 4 divisors (see below), whose sum is σ = 665810628. Its totient is φ = 665702400.

The previous prime is 665756491. The next prime is 665756537. The reversal of 665756513 is 315657566.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in 2 ways, for example, as 544382224 + 121374289 = 23332^2 + 11017^2 .

It is a cyclic number.

It is not a de Polignac number, because 665756513 - 2¹⁸ = 665494369 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665756543) 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, 1313 + ... + 36513.

It is an arithmetic number, because the mean of its divisors is an integer number (166452657).

Almost surely, 2^665756513 is an apocalyptic number.

It is an amenable number.

665756513 is a deficient number, since it is larger than the sum of its proper divisors (54115).

665756513 is a wasteful number, since it uses less digits than its factorization.

665756513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 54114.

The product of its digits is 567000, while the sum is 44.

The square root of 665756513 is about 25802.2579050749. The cubic root of 665756513 is about 873.1827374533.

The spelling of 665756513 in words is "six hundred sixty-five million, seven hundred fifty-six thousand, five hundred thirteen".