644331654 has 48 divisors (see below), whose sum is σ = 1502448480. Its totient is φ = 198823680.

The previous prime is 644331631. The next prime is 644331679. The reversal of 644331654 is 456133446.

644331654 is a `hidden beast` number, since 64 + 433 + 165 + 4 = 666.

644331654 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1407 + ... + 35925.

It is an arithmetic number, because the mean of its divisors is an integer number (31301010).

Almost surely, 2^644331654 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644331654, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (751224240).

644331654 is an abundant number, since it is smaller than the sum of its proper divisors (858116826).

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

644331654 is a wasteful number, since it uses less digits than its factorization.

644331654 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 34605 (or 34602 counting only the distinct ones).

The product of its digits is 103680, while the sum is 36.

The square root of 644331654 is about 25383.6887390308. The cubic root of 644331654 is about 863.7137281401.

The spelling of 644331654 in words is "six hundred forty-four million, three hundred thirty-one thousand, six hundred fifty-four".