643919155 has 16 divisors (see below), whose sum is σ = 879600384. Its totient is φ = 447942880.

The previous prime is 643919153. The next prime is 643919173. The reversal of 643919155 is 551919346.

643919155 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 643919155 - 2¹ = 643919153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643919153) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 253249 + ... + 255778.

It is an arithmetic number, because the mean of its divisors is an integer number (54975024).

Almost surely, 2^643919155 is an apocalyptic number.

643919155 is a deficient number, since it is larger than the sum of its proper divisors (235681229).

643919155 is a wasteful number, since it uses less digits than its factorization.

643919155 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 509066.

The product of its digits is 145800, while the sum is 43.

The square root of 643919155 is about 25375.5621612606. The cubic root of 643919155 is about 863.5293732332.

The spelling of 643919155 in words is "six hundred forty-three million, nine hundred nineteen thousand, one hundred fifty-five".