644961986949120 has 832 divisors, whose sum is σ = 2100785700142080. Its totient is φ = 168925593600000.

The previous prime is 644961986949031. The next prime is 644961986949127. The reversal of 644961986949120 is 21949689169446.

It is not an unprimeable number, because it can be changed into a prime (644961986949127) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 537020804520 + ... + 537020805720.

Almost surely, 2^{644961986949120} is an apocalyptic number.

644961986949120 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 644961986949120, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1050392850071040).

644961986949120 is an abundant number, since it is smaller than the sum of its proper divisors (1455823713192960).

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

644961986949120 is a wasteful number, since it uses less digits than its factorization.

644961986949120 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1940 (or 1918 counting only the distinct ones).

The product of its (nonzero) digits is 1451188224, while the sum is 78.

The spelling of 644961986949120 in words is "six hundred forty-four trillion, nine hundred sixty-one billion, nine hundred eighty-six million, nine hundred forty-nine thousand, one hundred twenty".