645968637 has 12 divisors (see below), whose sum is σ = 935743900. Its totient is φ = 429409728.

The previous prime is 645968599. The next prime is 645968651. The reversal of 645968637 is 736869546.

645968637 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 326488761 + 319479876 = 18069^2 + 17874^2 .

It is not a de Polignac number, because 645968637 - 2⁶ = 645968573 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 (645968537) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 99688 + ... + 105969.

Almost surely, 2^645968637 is an apocalyptic number.

It is an amenable number.

645968637 is a deficient number, since it is larger than the sum of its proper divisors (289775263).

645968637 is a wasteful number, since it uses less digits than its factorization.

645968637 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 206012 (or 206009 counting only the distinct ones).

The product of its digits is 6531840, while the sum is 54.

The square root of 645968637 is about 25415.9130664236. The cubic root of 645968637 is about 864.4445572614. Note that the first 3 decimals are identical.

Subtracting 645968637 from its reverse (736869546), we obtain a palindrome (90900909).

The spelling of 645968637 in words is "six hundred forty-five million, nine hundred sixty-eight thousand, six hundred thirty-seven".