643227917 has 6 divisors (see below), whose sum is σ = 666173898. Its totient is φ = 621046832.

The previous prime is 643227889. The next prime is 643227941. The reversal of 643227917 is 719722346.

It can be written as a sum of positive squares in 3 ways, for example, as 314494756 + 328733161 = 17734^2 + 18131^2 .

It is not a de Polignac number, because 643227917 - 2¹⁸ = 642965773 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 (643227217) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 381578 + ... + 383259.

It is an arithmetic number, because the mean of its divisors is an integer number (111028983).

Almost surely, 2^643227917 is an apocalyptic number.

It is an amenable number.

643227917 is a deficient number, since it is larger than the sum of its proper divisors (22945981).

643227917 is an equidigital number, since it uses as much as digits as its factorization.

643227917 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 764895 (or 764866 counting only the distinct ones).

The product of its digits is 127008, while the sum is 41.

The square root of 643227917 is about 25361.9383525787. The cubic root of 643227917 is about 863.2202671241.

The spelling of 643227917 in words is "six hundred forty-three million, two hundred twenty-seven thousand, nine hundred seventeen".