643426361 has 4 divisors (see below), whose sum is σ = 644383092. Its totient is φ = 642469632.

The previous prime is 643426339. The next prime is 643426409. The reversal of 643426361 is 163624346.

643426361 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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

It can be written as a sum of positive squares in 2 ways, for example, as 472627600 + 170798761 = 21740^2 + 13069^2 .

It is a cyclic number.

It is not a de Polignac number, because 643426361 - 2¹⁰ = 643425337 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643426321) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 477356 + ... + 478701.

It is an arithmetic number, because the mean of its divisors is an integer number (161095773).

Almost surely, 2^643426361 is an apocalyptic number.

It is an amenable number.

643426361 is a deficient number, since it is larger than the sum of its proper divisors (956731).

643426361 is an equidigital number, since it uses as much as digits as its factorization.

643426361 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 956730.

The product of its digits is 62208, while the sum is 35.

The square root of 643426361 is about 25365.8502912873. The cubic root of 643426361 is about 863.3090294767.

The spelling of 643426361 in words is "six hundred forty-three million, four hundred twenty-six thousand, three hundred sixty-one".