644442043245 has 256 divisors, whose sum is σ = 1497076826112. Its totient is φ = 227721461760.

The previous prime is 644442043243. The next prime is 644442043247. The reversal of 644442043245 is 542340244446.

It is an interprime number because it is at equal distance from previous prime (644442043243) and next prime (644442043247).

It is not a de Polignac number, because 644442043245 - 2¹ = 644442043243 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 644442043197 and 644442043206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644442043241) by changing a digit.

It is a polite number, since it can be written in 255 ways as a sum of consecutive naturals, for example, 11970127 + ... + 12023843.

It is an arithmetic number, because the mean of its divisors is an integer number (5847956352).

Almost surely, 2^644442043245 is an apocalyptic number.

644442043245 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

644442043245 is an abundant number, since it is smaller than the sum of its proper divisors (852634782867).

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

644442043245 is a wasteful number, since it uses less digits than its factorization.

644442043245 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 53820.

The product of its (nonzero) digits is 1474560, while the sum is 42.

The spelling of 644442043245 in words is "six hundred forty-four billion, four hundred forty-two million, forty-three thousand, two hundred forty-five".