645810646 has 16 divisors (see below), whose sum is σ = 1098140400. Its totient is φ = 282378528.

The previous prime is 645810643. The next prime is 645810653. The reversal of 645810646 is 646018546.

It is a happy number.

It is a junction number, because it is equal to n+sod(n) for n = 645810599 and 645810608.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645810643) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 653161 + ... + 654148.

It is an arithmetic number, because the mean of its divisors is an integer number (68633775).

Almost surely, 2^645810646 is an apocalyptic number.

645810646 is a deficient number, since it is larger than the sum of its proper divisors (452329754).

645810646 is a wasteful number, since it uses less digits than its factorization.

645810646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1307343.

The product of its (nonzero) digits is 138240, while the sum is 40.

The square root of 645810646 is about 25412.8047645277. The cubic root of 645810646 is about 864.3740762358.

The spelling of 645810646 in words is "six hundred forty-five million, eight hundred ten thousand, six hundred forty-six".