643500000001 has 4 divisors (see below), whose sum is σ = 643571756100. Its totient is φ = 643428243904.

The previous prime is 643499999957. The next prime is 643500000053. The reversal of 643500000001 is 100000005346.

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 418990817025 + 224509182976 = 647295^2 + 473824^2 .

It is a cyclic number.

It is not a de Polignac number, because 643500000001 - 2⁹ = 643499999489 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643500000301) 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, 35864596 + ... + 35882533.

It is an arithmetic number, because the mean of its divisors is an integer number (160892939025).

Almost surely, 2^643500000001 is an apocalyptic number.

It is an amenable number.

643500000001 is a deficient number, since it is larger than the sum of its proper divisors (71756099).

643500000001 is an equidigital number, since it uses as much as digits as its factorization.

643500000001 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 71756098.

The product of its (nonzero) digits is 360, while the sum is 19.

Adding to 643500000001 its reverse (100000005346), we get a palindrome (743500005347).

The spelling of 643500000001 in words is "six hundred forty-three billion, five hundred million, one", and thus it is an aban number.