644533464468 has 96 divisors (see below), whose sum is σ = 1635825639168. Its totient is φ = 196692019200.

The previous prime is 644533464371. The next prime is 644533464469. The reversal of 644533464468 is 864464335446.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644533464469) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 39701913 + ... + 39718143.

It is an arithmetic number, because the mean of its divisors is an integer number (17039850408).

Almost surely, 2^644533464468 is an apocalyptic number.

644533464468 is a gapful number since it is divisible by the number (68) 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 644533464468, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (817912819584).

644533464468 is an abundant number, since it is smaller than the sum of its proper divisors (991292174700).

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

644533464468 is a wasteful number, since it uses less digits than its factorization.

644533464468 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21553 (or 21551 counting only the distinct ones).

The product of its digits is 79626240, while the sum is 57.

The spelling of 644533464468 in words is "six hundred forty-four billion, five hundred thirty-three million, four hundred sixty-four thousand, four hundred sixty-eight".