643958418449 has 4 divisors (see below), whose sum is σ = 659664721380. Its totient is φ = 628252115520.

The previous prime is 643958418437. The next prime is 643958418487. The reversal of 643958418449 is 944814859346.

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 194780995600 + 449177422849 = 441340^2 + 670207^2 .

It is a cyclic number.

It is not a de Polignac number, because 643958418449 - 2¹⁶ = 643958352913 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643958418419) 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, 7853151404 + ... + 7853151485.

It is an arithmetic number, because the mean of its divisors is an integer number (164916180345).

Almost surely, 2^643958418449 is an apocalyptic number.

It is an amenable number.

643958418449 is a deficient number, since it is larger than the sum of its proper divisors (15706302931).

643958418449 is a wasteful number, since it uses less digits than its factorization.

643958418449 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15706302930.

The product of its digits is 119439360, while the sum is 65.

The spelling of 643958418449 in words is "six hundred forty-three billion, nine hundred fifty-eight million, four hundred eighteen thousand, four hundred forty-nine".