643616455 has 4 divisors (see below), whose sum is σ = 772339752. Its totient is φ = 514893160.

The previous prime is 643616423. The next prime is 643616461. The reversal of 643616455 is 554616346.

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

It is not a de Polignac number, because 643616455 - 2⁵ = 643616423 is a prime.

It is a super-2 number, since 2×643616455² = 828484282293534050, which contains 22 as substring.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 64361641 + ... + 64361650.

It is an arithmetic number, because the mean of its divisors is an integer number (193084938).

Almost surely, 2^643616455 is an apocalyptic number.

643616455 is a deficient number, since it is larger than the sum of its proper divisors (128723297).

643616455 is a wasteful number, since it uses less digits than its factorization.

643616455 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128723296.

The product of its digits is 259200, while the sum is 40.

The square root of 643616455 is about 25369.5970602609. The cubic root of 643616455 is about 863.3940398305.

The spelling of 643616455 in words is "six hundred forty-three million, six hundred sixteen thousand, four hundred fifty-five".