645506736 has 160 divisors (see below), whose sum is σ = 1976778240. Its totient is φ = 177666048.

The previous prime is 645506731. The next prime is 645506749. The reversal of 645506736 is 637605546.

645506736 = 63² + 64² + ... + 1246².

645506736 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 not an unprimeable number, because it can be changed into a prime (645506731) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1702995 + ... + 1703373.

It is an arithmetic number, because the mean of its divisors is an integer number (12354864).

Almost surely, 2^645506736 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 645506736, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (988389120).

645506736 is an abundant number, since it is smaller than the sum of its proper divisors (1331271504).

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

645506736 is a wasteful number, since it uses less digits than its factorization.

645506736 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 571 (or 565 counting only the distinct ones).

The product of its (nonzero) digits is 453600, while the sum is 42.

The square root of 645506736 is about 25406.8245949784. The cubic root of 645506736 is about 864.2384672694.

The spelling of 645506736 in words is "six hundred forty-five million, five hundred six thousand, seven hundred thirty-six".