665818464529 has 3 divisors (see below), whose sum is σ = 665819280507. Its totient is φ = 665817648552.

The previous prime is 665818464481. The next prime is 665818464547. The reversal of 665818464529 is 925464818566.

It is a happy number.

The square root of 665818464529 is 815977.

It is a perfect power (a square), and thus also a powerful number.

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 only one way, i.e., 1997643025 + 663820821504 = 44695^2 + 814752^2 .

It is not a de Polignac number, because 665818464529 - 2¹¹ = 665818462481 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (665818464559) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 407989 + ... + 1223965.

It is an arithmetic number, because the mean of its divisors is an integer number (221939760169).

Almost surely, 2^665818464529 is an apocalyptic number.

665818464529 is the 815977-th square number.

665818464529 is the 407989-th centered octagonal number.

It is an amenable number.

665818464529 is a deficient number, since it is larger than the sum of its proper divisors (815978).

665818464529 is an frugal number, since it uses more digits than its factorization.

665818464529 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1631954 (or 815977 counting only the distinct ones).

The product of its digits is 99532800, while the sum is 64.

Multiplying 665818464529 by its sum of digits (64), we get a square (42612381729856 = 6527816²).

The spelling of 665818464529 in words is "six hundred sixty-five billion, eight hundred eighteen million, four hundred sixty-four thousand, five hundred twenty-nine".