643261847 has 4 divisors (see below), whose sum is σ = 665443320. Its totient is φ = 621080376.

The previous prime is 643261831. The next prime is 643261867. The reversal of 643261847 is 748162346.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 748162346 = 2 ⋅374081173.

It is a cyclic number.

It is not a de Polignac number, because 643261847 - 2⁴ = 643261831 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 (643261867) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11090693 + ... + 11090750.

It is an arithmetic number, because the mean of its divisors is an integer number (166360830).

Almost surely, 2^643261847 is an apocalyptic number.

643261847 is a deficient number, since it is larger than the sum of its proper divisors (22181473).

643261847 is a wasteful number, since it uses less digits than its factorization.

643261847 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22181472.

The product of its digits is 193536, while the sum is 41.

The square root of 643261847 is about 25362.6072595071. The cubic root of 643261847 is about 863.2354450250.

The spelling of 643261847 in words is "six hundred forty-three million, two hundred sixty-one thousand, eight hundred forty-seven".