644828026808 has 16 divisors (see below), whose sum is σ = 1381774343280. Its totient is φ = 276354868608.

The previous prime is 644828026807. The next prime is 644828026861. The reversal of 644828026808 is 808620828446.

It is a happy number.

It is a super-3 number, since 3×644828026808³ (a number of 36 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (56), and also a Moran number because the ratio is a prime number: 11514786193 = 644828026808 / (6 + 4 + 4 + 8 + 2 + 8 + 0 + 2 + 6 + 8 + 0 + 8).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644828026807) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5757393041 + ... + 5757393152.

It is an arithmetic number, because the mean of its divisors is an integer number (86360896455).

Almost surely, 2^644828026808 is an apocalyptic number.

It is an amenable number.

644828026808 is an abundant number, since it is smaller than the sum of its proper divisors (736946316472).

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

644828026808 is a wasteful number, since it uses less digits than its factorization.

644828026808 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11514786206 (or 11514786202 counting only the distinct ones).

The product of its (nonzero) digits is 9437184, while the sum is 56.

The spelling of 644828026808 in words is "six hundred forty-four billion, eight hundred twenty-eight million, twenty-six thousand, eight hundred eight".