643123549 has 18 divisors (see below), whose sum is σ = 698033882. Its totient is φ = 592252800.

The previous prime is 643123543. The next prime is 643123561. The reversal of 643123549 is 945321346.

643123549 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 3 ways, for example, as 91202500 + 551921049 = 9550^2 + 23493^2 .

It is not a de Polignac number, because 643123549 - 2⁷ = 643123421 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643123543) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 3367044 + ... + 3367234.

Almost surely, 2^643123549 is an apocalyptic number.

It is an amenable number.

643123549 is a deficient number, since it is larger than the sum of its proper divisors (54910333).

643123549 is an equidigital number, since it uses as much as digits as its factorization.

643123549 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 477 (or 269 counting only the distinct ones).

The product of its digits is 77760, while the sum is 37.

The square root of 643123549 is about 25359.8806976689. The cubic root of 643123549 is about 863.1735768589.

The spelling of 643123549 in words is "six hundred forty-three million, one hundred twenty-three thousand, five hundred forty-nine".