643654217 has 8 divisors (see below), whose sum is σ = 666539400. Its totient is φ = 620815104.

The previous prime is 643654129. The next prime is 643654259. The reversal of 643654217 is 712456346.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 89946256 + 553707961 = 9484^2 + 23531^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 643654217 - 2¹² = 643650121 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643654717) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 18263 + ... + 40259.

It is an arithmetic number, because the mean of its divisors is an integer number (83317425).

Almost surely, 2^643654217 is an apocalyptic number.

It is an amenable number.

643654217 is a deficient number, since it is larger than the sum of its proper divisors (22885183).

643654217 is a wasteful number, since it uses less digits than its factorization.

643654217 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23035.

The product of its digits is 120960, while the sum is 38.

The square root of 643654217 is about 25370.3412866284. The cubic root of 643654217 is about 863.4109250670.

The spelling of 643654217 in words is "six hundred forty-three million, six hundred fifty-four thousand, two hundred seventeen".