644400230400 has 1872 divisors, whose sum is σ = 2661904627200. Its totient is φ = 153837895680.

The previous prime is 644400230363. The next prime is 644400230437. The reversal of 644400230400 is 4032004446.

It is an interprime number because it is at equal distance from previous prime (644400230363) and next prime (644400230437).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 13710643177 + ... + 13710643223.

It is an arithmetic number, because the mean of its divisors is an integer number (1421957600).

Almost surely, 2^644400230400 is an apocalyptic number.

644400230400 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 644400230400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1330952313600).

644400230400 is an abundant number, since it is smaller than the sum of its proper divisors (2017504396800).

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

644400230400 is a wasteful number, since it uses less digits than its factorization.

644400230400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 144 (or 105 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 27.

Adding to 644400230400 its reverse (4032004446), we get a palindrome (648432234846).

The spelling of 644400230400 in words is "six hundred forty-four billion, four hundred million, two hundred thirty thousand, four hundred".