645663744000 has 1344 divisors, whose sum is σ = 2637736395840. Its totient is φ = 155713536000.

The previous prime is 645663743987. The next prime is 645663744071. The reversal of 645663744000 is 447366546.

It is a happy number.

645663744000 is a `hidden beast` number, since 6 + 4 + 5 + 6 + 637 + 4 + 4 + 0 + 0 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 3345407904 + ... + 3345408096.

It is an arithmetic number, because the mean of its divisors is an integer number (1962601485).

Almost surely, 2^645663744000 is an apocalyptic number.

645663744000 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 645663744000, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1318868197920).

645663744000 is an abundant number, since it is smaller than the sum of its proper divisors (1992072651840).

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

645663744000 is a wasteful number, since it uses less digits than its factorization.

645663744000 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 265 (or 214 counting only the distinct ones).

The product of its (nonzero) digits is 1451520, while the sum is 45.

The spelling of 645663744000 in words is "six hundred forty-five billion, six hundred sixty-three million, seven hundred forty-four thousand".