645737664 has 224 divisors, whose sum is σ = 2078979840. Its totient is φ = 174182400.

The previous prime is 645737641. The next prime is 645737669. The reversal of 645737664 is 466737546.

It is a Harshad number since it is a multiple of its sum of digits (48).

It is not an unprimeable number, because it can be changed into a prime (645737669) 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, 795819 + ... + 796629.

It is an arithmetic number, because the mean of its divisors is an integer number (9281160).

Almost surely, 2^645737664 is an apocalyptic number.

645737664 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645737664, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1039489920).

645737664 is an abundant number, since it is smaller than the sum of its proper divisors (1433242176).

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

645737664 is a wasteful number, since it uses less digits than its factorization.

645737664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 879 (or 869 counting only the distinct ones).

The product of its digits is 2540160, while the sum is 48.

The square root of 645737664 is about 25411.3687943015. The cubic root of 645737664 is about 864.3415145112.

The spelling of 645737664 in words is "six hundred forty-five million, seven hundred thirty-seven thousand, six hundred sixty-four".