644971547460240 has 9600 divisors, whose sum is σ = 3347129769984000. Its totient is φ = 111564125798400.

The previous prime is 644971547460211. The next prime is 644971547460241. The reversal of 644971547460240 is 42064745179446.

644971547460240 is a `hidden beast` number, since 6 + 4 + 4 + 9 + 7 + 1 + 547 + 4 + 60 + 24 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is not an unprimeable number, because it can be changed into a prime (644971547460241) by changing a digit.

It is a polite number, since it can be written in 1919 ways as a sum of consecutive naturals, for example, 4328668103686 + ... + 4328668103834.

It is an arithmetic number, because the mean of its divisors is an integer number (348659351040).

Almost surely, 2^{644971547460240} is an apocalyptic number.

644971547460240 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 644971547460240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1673564884992000).

644971547460240 is an abundant number, since it is smaller than the sum of its proper divisors (2702158222523760).

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

644971547460240 is a wasteful number, since it uses less digits than its factorization.

644971547460240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 369 (or 343 counting only the distinct ones).

The product of its (nonzero) digits is 162570240, while the sum is 63.

The spelling of 644971547460240 in words is "six hundred forty-four trillion, nine hundred seventy-one billion, five hundred forty-seven million, four hundred sixty thousand, two hundred forty".