645640960 has 72 divisors (see below), whose sum is σ = 1637538336. Its totient is φ = 243056640.

The previous prime is 645640921. The next prime is 645641041. The reversal of 645640960 is 69046546.

It is a hoax number, since the sum of its digits (40) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6925 + ... + 36595.

It is an arithmetic number, because the mean of its divisors is an integer number (22743588).

Almost surely, 2^645640960 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 645640960, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (818769168).

645640960 is an abundant number, since it is smaller than the sum of its proper divisors (991897376).

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

645640960 is a wasteful number, since it uses less digits than its factorization.

645640960 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29709 (or 29695 counting only the distinct ones).

The product of its (nonzero) digits is 155520, while the sum is 40.

The square root of 645640960 is about 25409.4659526720. The cubic root of 645640960 is about 864.2983651750.

The spelling of 645640960 in words is "six hundred forty-five million, six hundred forty thousand, nine hundred sixty".