664780946281 has 3 divisors (see below), whose sum is σ = 664781761623. Its totient is φ = 664780130940.

The previous prime is 664780946257. The next prime is 664780946317. The reversal of 664780946281 is 182649087466.

The square root of 664780946281 is 815341.

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., 139532878681 + 525248067600 = 373541^2 + 724740^2 .

It is not a de Polignac number, because 664780946281 - 2²⁷ = 664646728553 is a prime.

It is a super-2 number, since 2×664780946281² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (664784946281) 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 2 ways as a sum of consecutive naturals, for example, 407671 + ... + 1223011.

It is an arithmetic number, because the mean of its divisors is an integer number (221593920541).

Almost surely, 2^664780946281 is an apocalyptic number.

664780946281 is the 815341-st square number.

664780946281 is the 407671-st centered octagonal number.

It is an amenable number.

664780946281 is a deficient number, since it is larger than the sum of its proper divisors (815342).

664780946281 is an frugal number, since it uses more digits than its factorization.

664780946281 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1630682 (or 815341 counting only the distinct ones).

The product of its (nonzero) digits is 27869184, while the sum is 61.

The spelling of 664780946281 in words is "six hundred sixty-four billion, seven hundred eighty million, nine hundred forty-six thousand, two hundred eighty-one".