643887625 has 16 divisors (see below), whose sum is σ = 811543824. Its totient is φ = 510000000.

The previous prime is 643887623. The next prime is 643887641. The reversal of 643887625 is 526788346.

It can be written as a sum of positive squares in 8 ways, for example, as 13927824 + 629959801 = 3732^2 + 25099^2 .

It is not a de Polignac number, because 643887625 - 2¹ = 643887623 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643887623) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 12876 + ... + 38125.

It is an arithmetic number, because the mean of its divisors is an integer number (50721489).

Almost surely, 2^643887625 is an apocalyptic number.

It is an amenable number.

643887625 is a deficient number, since it is larger than the sum of its proper divisors (167656199).

643887625 is a wasteful number, since it uses less digits than its factorization.

643887625 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51117 (or 51107 counting only the distinct ones).

The product of its digits is 1935360, while the sum is 49.

The square root of 643887625 is about 25374.9408866307. The cubic root of 643887625 is about 863.5152785417.

The spelling of 643887625 in words is "six hundred forty-three million, eight hundred eighty-seven thousand, six hundred twenty-five".