645181645824 has 165 divisors, whose sum is σ = 1927329577657. Its totient is φ = 214983438336.

The previous prime is 645181645817. The next prime is 645181645837. The reversal of 645181645824 is 428546181546.

The square root of 645181645824 is 803232.

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

645181645824 is a `hidden beast` number, since 6 + 4 + 5 + 181 + 6 + 458 + 2 + 4 = 666.

It can be written as a sum of positive squares in only one way, i.e., 405473485824 + 239708160000 = 636768^2 + 489600^2 .

It is a super-2 number, since 2×645181645824² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 14 ways as a sum of consecutive naturals, for example, 231329422 + ... + 231332210.

Almost surely, 2^645181645824 is an apocalyptic number.

645181645824 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

645181645824 is the 803232-nd square number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 645181645824

645181645824 is an abundant number, since it is smaller than the sum of its proper divisors (1282147931833).

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

645181645824 is an frugal number, since it uses more digits than its factorization.

645181645824 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5610 (or 2794 counting only the distinct ones).

The product of its digits is 7372800, while the sum is 54.

The spelling of 645181645824 in words is "six hundred forty-five billion, one hundred eighty-one million, six hundred forty-five thousand, eight hundred twenty-four".