645371664 has 80 divisors (see below), whose sum is σ = 1945970688. Its totient is φ = 180464256.

The previous prime is 645371659. The next prime is 645371681. The reversal of 645371664 is 466173546.

645371664 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4642 + ... + 36225.

Almost surely, 2^645371664 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 645371664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (972985344).

645371664 is an abundant number, since it is smaller than the sum of its proper divisors (1300599024).

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

645371664 is a wasteful number, since it uses less digits than its factorization.

645371664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40932 (or 40926 counting only the distinct ones).

The product of its digits is 362880, while the sum is 42.

The square root of 645371664 is about 25404.1662724837. The cubic root of 645371664 is about 864.1781825582.

The spelling of 645371664 in words is "six hundred forty-five million, three hundred seventy-one thousand, six hundred sixty-four".