644080667555 has 48 divisors (see below), whose sum is σ = 870815576736. Its totient is φ = 454581980160.

The previous prime is 644080667491. The next prime is 644080667623. The reversal of 644080667555 is 555766080446.

It is not a de Polignac number, because 644080667555 - 2⁶ = 644080667491 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644080667555.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 46791104 + ... + 46804866.

It is an arithmetic number, because the mean of its divisors is an integer number (18141991182).

Almost surely, 2^644080667555 is an apocalyptic number.

644080667555 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

644080667555 is a deficient number, since it is larger than the sum of its proper divisors (226734909181).

644080667555 is a wasteful number, since it uses less digits than its factorization.

644080667555 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15188 (or 15165 counting only the distinct ones).

The product of its (nonzero) digits is 24192000, while the sum is 56.

The spelling of 644080667555 in words is "six hundred forty-four billion, eighty million, six hundred sixty-seven thousand, five hundred fifty-five".