645824981880 has 768 divisors, whose sum is σ = 2478058128000. Its totient is φ = 144473849856.

The previous prime is 645824981863. The next prime is 645824981881. The reversal of 645824981880 is 88189428546.

645824981880 is a `hidden beast` number, since 6 + 4 + 58 + 2 + 498 + 18 + 80 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (645824981881) by changing a digit.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 240171576 + ... + 240174264.

Almost surely, 2^645824981880 is an apocalyptic number.

645824981880 is a gapful number since it is divisible by the number (60) 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 645824981880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1239029064000).

645824981880 is an abundant number, since it is smaller than the sum of its proper divisors (1832233146120).

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

645824981880 is a wasteful number, since it uses less digits than its factorization.

645824981880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2848 (or 2841 counting only the distinct ones).

The product of its (nonzero) digits is 35389440, while the sum is 63.

The spelling of 645824981880 in words is "six hundred forty-five billion, eight hundred twenty-four million, nine hundred eighty-one thousand, eight hundred eighty".