643755925 has 6 divisors (see below), whose sum is σ = 798257378. Its totient is φ = 515004720.

The previous prime is 643755919. The next prime is 643755941. The reversal of 643755925 is 529557346.

It can be written as a sum of positive squares in 3 ways, for example, as 223382916 + 420373009 = 14946^2 + 20503^2 .

It is not a de Polignac number, because 643755925 - 2¹⁹ = 643231637 is a prime.

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, 12875094 + ... + 12875143.

Almost surely, 2^643755925 is an apocalyptic number.

It is an amenable number.

643755925 is a deficient number, since it is larger than the sum of its proper divisors (154501453).

643755925 is a wasteful number, since it uses less digits than its factorization.

643755925 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25750247 (or 25750242 counting only the distinct ones).

The product of its digits is 1134000, while the sum is 46.

The square root of 643755925 is about 25372.3456739813. The cubic root of 643755925 is about 863.4564004019.

It can be divided in two parts, 643755 and 925, that added together give a triangular number (644680 = T₁₁₃₅).

The spelling of 643755925 in words is "six hundred forty-three million, seven hundred fifty-five thousand, nine hundred twenty-five".