645814644 has 12 divisors (see below), whose sum is σ = 1506900864. Its totient is φ = 215271544.

The previous prime is 645814643. The next prime is 645814667. The reversal of 645814644 is 446418546.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (12).

It is a junction number, because it is equal to n+sod(n) for n = 645814596 and 645814605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645814643) 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 3 ways as a sum of consecutive naturals, for example, 26908932 + ... + 26908955.

It is an arithmetic number, because the mean of its divisors is an integer number (125575072).

Almost surely, 2^645814644 is an apocalyptic number.

It is an amenable number.

645814644 is an abundant number, since it is smaller than the sum of its proper divisors (861086220).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

645814644 is a wasteful number, since it uses less digits than its factorization.

645814644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53817894 (or 53817892 counting only the distinct ones).

The product of its digits is 368640, while the sum is 42.

The square root of 645814644 is about 25412.8834255383. The cubic root of 645814644 is about 864.3758599168.

The spelling of 645814644 in words is "six hundred forty-five million, eight hundred fourteen thousand, six hundred forty-four".