643337965 has 4 divisors (see below), whose sum is σ = 772005564. Its totient is φ = 514670368.

The previous prime is 643337963. The next prime is 643337969. The reversal of 643337965 is 569733346.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 79085449 + 564252516 = 8893^2 + 23754^2 .

It is a cyclic number.

It is not a de Polignac number, because 643337965 - 2¹ = 643337963 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643337963) 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, 64333792 + ... + 64333801.

It is an arithmetic number, because the mean of its divisors is an integer number (193001391).

Almost surely, 2^643337965 is an apocalyptic number.

It is an amenable number.

643337965 is a deficient number, since it is larger than the sum of its proper divisors (128667599).

643337965 is a wasteful number, since it uses less digits than its factorization.

643337965 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 128667598.

The product of its digits is 1224720, while the sum is 46.

The square root of 643337965 is about 25364.1078100532. The cubic root of 643337965 is about 863.2694929348.

The spelling of 643337965 in words is "six hundred forty-three million, three hundred thirty-seven thousand, nine hundred sixty-five".