645065718644736 has 315 divisors, whose sum is σ = 1934516496928981. Its totient is φ = 214992647553024.

The previous prime is 645065718644719. The next prime is 645065718644801. The reversal of 645065718644736 is 637446817560546.

The square root of 645065718644736 is 25398144.

It is a perfect power (a square), and thus also a powerful number.

645065718644736 is a `hidden beast` number, since 6 + 4 + 5 + 0 + 6 + 5 + 71 + 86 + 4 + 473 + 6 = 666.

It can be written as a sum of positive squares in only one way, i.e., 444288154484736 + 200777564160000 = 21078144^2 + 14169600^2 .

It is a super-2 number, since 2×645065718644736² (a number of 30 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 20 ways as a sum of consecutive naturals, for example, 87775981990 + ... + 87775989338.

Almost surely, 2^{645065718644736} is an apocalyptic number.

645065718644736 is the 25398144-th square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645065718644736

645065718644736 is an abundant number, since it is smaller than the sum of its proper divisors (1289450778284245).

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

645065718644736 is an frugal number, since it uses more digits than its factorization.

645065718644736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 14744 (or 7354 counting only the distinct ones).

The product of its (nonzero) digits is 2438553600, while the sum is 72.

The spelling of 645065718644736 in words is "six hundred forty-five trillion, sixty-five billion, seven hundred eighteen million, six hundred forty-four thousand, seven hundred thirty-six".