644523273464 has 64 divisors (see below), whose sum is σ = 1400999846400. Its totient is φ = 272250921600.

The previous prime is 644523273463. The next prime is 644523273487. The reversal of 644523273464 is 464372325446.

It is a happy number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644523273463) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 14056127 + ... + 14101905.

It is an arithmetic number, because the mean of its divisors is an integer number (21890622600).

Almost surely, 2^644523273464 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644523273464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (700499923200).

644523273464 is an abundant number, since it is smaller than the sum of its proper divisors (756476572936).

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

644523273464 is a wasteful number, since it uses less digits than its factorization.

644523273464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49404 (or 49400 counting only the distinct ones).

The product of its digits is 11612160, while the sum is 50.

The spelling of 644523273464 in words is "six hundred forty-four billion, five hundred twenty-three million, two hundred seventy-three thousand, four hundred sixty-four".