645336638 has 16 divisors (see below), whose sum is σ = 992431440. Its totient is φ = 314539200.

The previous prime is 645336619. The next prime is 645336667. The reversal of 645336638 is 836633546.

It is a congruent number.

It is an unprimeable number.

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, 130328 + ... + 135188.

It is an arithmetic number, because the mean of its divisors is an integer number (62026965).

Almost surely, 2^645336638 is an apocalyptic number.

645336638 is a deficient number, since it is larger than the sum of its proper divisors (347094802).

645336638 is a wasteful number, since it uses less digits than its factorization.

645336638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6523.

The product of its digits is 933120, while the sum is 44.

The square root of 645336638 is about 25403.4768880167. The cubic root of 645336638 is about 864.1625485423.

The spelling of 645336638 in words is "six hundred forty-five million, three hundred thirty-six thousand, six hundred thirty-eight".