644340055 has 16 divisors (see below), whose sum is σ = 808727040. Its totient is φ = 491898528.

The previous prime is 644340043. The next prime is 644340071. The reversal of 644340055 is 550043446.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644340055 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 644339999 and 644340026.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 44104 + ... + 56866.

It is an arithmetic number, because the mean of its divisors is an integer number (50545440).

Almost surely, 2^644340055 is an apocalyptic number.

644340055 is a deficient number, since it is larger than the sum of its proper divisors (164386985).

644340055 is a wasteful number, since it uses less digits than its factorization.

644340055 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13230.

The product of its (nonzero) digits is 28800, while the sum is 31.

The square root of 644340055 is about 25383.8542187746. The cubic root of 644340055 is about 863.7174819147.

The spelling of 644340055 in words is "six hundred forty-four million, three hundred forty thousand, fifty-five".