640000025 has 18 divisors (see below), whose sum is σ = 923169150. Its totient is φ = 438856320.

The previous prime is 640000019. The next prime is 640000027. The reversal of 640000025 is 520000046.

It can be written as a sum of positive squares in 3 ways, for example, as 1073296 + 638926729 = 1036^2 + 25277^2 .

It is not a de Polignac number, because 640000025 - 2⁸ = 639999769 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 639999958 and 640000012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (640000027) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 260000 + ... + 262449.

It is an arithmetic number, because the mean of its divisors is an integer number (51287175).

Almost surely, 2^640000025 is an apocalyptic number.

It is an amenable number.

640000025 is a deficient number, since it is larger than the sum of its proper divisors (283169125).

640000025 is a wasteful number, since it uses less digits than its factorization.

640000025 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 522473 (or 522461 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 640000025 is about 25298.2217754529. The cubic root of 640000025 is about 861.7738872338.

The spelling of 640000025 in words is "six hundred forty million, twenty-five", and thus it is an aban number.