643281769 has 9 divisors (see below), whose sum is σ = 696928599. Its totient is φ = 593494200.

The previous prime is 643281761. The next prime is 643281791. The reversal of 643281769 is 967182346.

The square root of 643281769 is 25363.

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

It can be written as a sum of positive squares in only one way, i.e., 95160025 + 548121744 = 9755^2 + 23412^2 .

It is not a de Polignac number, because 643281769 - 2³ = 643281761 is a prime.

It is a super-2 number, since 2×643281769² = 827622868655538722, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643281761) 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 8 ways as a sum of consecutive naturals, for example, 328744 + ... + 330694.

It is an arithmetic number, because the mean of its divisors is an integer number (77436511).

Almost surely, 2^643281769 is an apocalyptic number.

643281769 is the 25363-rd square number.

643281769 is the 12682-nd centered octagonal number.

It is an amenable number.

643281769 is a deficient number, since it is larger than the sum of its proper divisors (53646830).

643281769 is an frugal number, since it uses more digits than its factorization.

643281769 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3928 (or 1964 counting only the distinct ones).

The product of its digits is 435456, while the sum is 46.

The cubic root of 643281769 is about 863.2443564810.

The spelling of 643281769 in words is "six hundred forty-three million, two hundred eighty-one thousand, seven hundred sixty-nine".