643531655 has 8 divisors (see below), whose sum is σ = 831640992. Its totient is φ = 475223328.

The previous prime is 643531633. The next prime is 643531667. The reversal of 643531655 is 556135346.

643531655 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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 643531655 - 2¹⁶ = 643466119 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4950179 + ... + 4950308.

It is an arithmetic number, because the mean of its divisors is an integer number (103955124).

Almost surely, 2^643531655 is an apocalyptic number.

643531655 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

643531655 is a deficient number, since it is larger than the sum of its proper divisors (188109337).

643531655 is a wasteful number, since it uses less digits than its factorization.

643531655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9900505.

The product of its digits is 162000, while the sum is 38.

The square root of 643531655 is about 25367.9257133886. The cubic root of 643531655 is about 863.3561191974.

The spelling of 643531655 in words is "six hundred forty-three million, five hundred thirty-one thousand, six hundred fifty-five".