643654606417 has 4 divisors (see below), whose sum is σ = 643806380196. Its totient is φ = 643502832640.

The previous prime is 643654606393. The next prime is 643654606423. The reversal of 643654606417 is 714606456346.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 714606456346 = 2 ⋅357303228173.

It can be written as a sum of positive squares in 2 ways, for example, as 626700222736 + 16954383681 = 791644^2 + 130209^2 .

It is a cyclic number.

It is not a de Polignac number, because 643654606417 - 2⁷ = 643654606289 is a prime.

It is a super-3 number, since 3×643654606417³ (a number of 36 digits) contains 333 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643654606477) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 75880528 + ... + 75889009.

It is an arithmetic number, because the mean of its divisors is an integer number (160951595049).

Almost surely, 2^643654606417 is an apocalyptic number.

It is an amenable number.

643654606417 is a deficient number, since it is larger than the sum of its proper divisors (151773779).

643654606417 is a wasteful number, since it uses less digits than its factorization.

643654606417 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 151773778.

The product of its (nonzero) digits is 8709120, while the sum is 52.

The spelling of 643654606417 in words is "six hundred forty-three billion, six hundred fifty-four million, six hundred six thousand, four hundred seventeen".