643611775 has 6 divisors (see below), whose sum is σ = 798078632. Its totient is φ = 514889400.

The previous prime is 643611767. The next prime is 643611791. The reversal of 643611775 is 577116346.

It is not a de Polignac number, because 643611775 - 2³ = 643611767 is a prime.

It is a super-2 number, since 2×643611775² = 828472233837301250, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 12872211 + ... + 12872260.

Almost surely, 2^643611775 is an apocalyptic number.

643611775 is a deficient number, since it is larger than the sum of its proper divisors (154466857).

643611775 is a wasteful number, since it uses less digits than its factorization.

643611775 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25744481 (or 25744476 counting only the distinct ones).

The product of its digits is 105840, while the sum is 40.

The square root of 643611775 is about 25369.5048237052. The cubic root of 643611775 is about 863.3919471277.

The spelling of 643611775 in words is "six hundred forty-three million, six hundred eleven thousand, seven hundred seventy-five".