645970128 has 80 divisors (see below), whose sum is σ = 1742834880. Its totient is φ = 205907968.

The previous prime is 645970109. The next prime is 645970139. The reversal of 645970128 is 821079546.

It is a self number, because there is not a number n which added to its sum of digits gives 645970128.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 146776 + ... + 151112.

It is an arithmetic number, because the mean of its divisors is an integer number (21785436).

Almost surely, 2^645970128 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645970128, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (871417440).

645970128 is an abundant number, since it is smaller than the sum of its proper divisors (1096864752).

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

645970128 is a wasteful number, since it uses less digits than its factorization.

645970128 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4484 (or 4478 counting only the distinct ones).

The product of its (nonzero) digits is 120960, while the sum is 42.

The square root of 645970128 is about 25415.9423984239. The cubic root of 645970128 is about 864.4452223534.

The spelling of 645970128 in words is "six hundred forty-five million, nine hundred seventy thousand, one hundred twenty-eight".