644935987080 has 2592 divisors, whose sum is σ = 3027926603520. Its totient is φ = 122863910400.

The previous prime is 644935987079. The next prime is 644935987081. The reversal of 644935987080 is 80789539446.

644935987080 is a `hidden beast` number, since 6 + 449 + 35 + 9 + 87 + 0 + 80 = 666.

It is an interprime number because it is at equal distance from previous prime (644935987079) and next prime (644935987081).

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

It is a junction number, because it is equal to n+sod(n) for n = 644935986999 and 644935987017.

It is not an unprimeable number, because it can be changed into a prime (644935987081) by changing a digit.

It is a polite number, since it can be written in 647 ways as a sum of consecutive naturals, for example, 20804386665 + ... + 20804386695.

It is an arithmetic number, because the mean of its divisors is an integer number (1168181560).

Almost surely, 2^644935987080 is an apocalyptic number.

644935987080 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 644935987080, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1513963301760).

644935987080 is an abundant number, since it is smaller than the sum of its proper divisors (2382990616440).

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

644935987080 is a wasteful number, since it uses less digits than its factorization.

644935987080 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 131 (or 78 counting only the distinct ones).

The product of its (nonzero) digits is 52254720, while the sum is 63.

The spelling of 644935987080 in words is "six hundred forty-four billion, nine hundred thirty-five million, nine hundred eighty-seven thousand, eighty".