643653331 has 4 divisors (see below), whose sum is σ = 645334272. Its totient is φ = 641972392.

The previous prime is 643653323. The next prime is 643653379. The reversal of 643653331 is 133356346.

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

It is a cyclic number.

It is not a de Polignac number, because 643653331 - 2³ = 643653323 is a prime.

It is a super-3 number, since 3×643653331³ (a number of 27 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643653431) 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, 839896 + ... + 840661.

It is an arithmetic number, because the mean of its divisors is an integer number (161333568).

Almost surely, 2^643653331 is an apocalyptic number.

643653331 is a deficient number, since it is larger than the sum of its proper divisors (1680941).

643653331 is a wasteful number, since it uses less digits than its factorization.

643653331 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1680940.

The product of its digits is 58320, while the sum is 34.

The square root of 643653331 is about 25370.3238252885. The cubic root of 643653331 is about 863.4105289006.

The spelling of 643653331 in words is "six hundred forty-three million, six hundred fifty-three thousand, three hundred thirty-one".