644554044 has 24 divisors (see below), whose sum is σ = 1671066320. Its totient is φ = 214851312.

The previous prime is 644554037. The next prime is 644554049. The reversal of 644554044 is 440455446.

644554044 is a `hidden beast` number, since 64 + 4 + 554 + 0 + 44 = 666.

It is a super-3 number, since 3×644554044³ (a number of 27 digits) contains 333 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644554049) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2983939 + ... + 2984154.

Almost surely, 2^644554044 is an apocalyptic number.

It is an amenable number.

644554044 is an abundant number, since it is smaller than the sum of its proper divisors (1026512276).

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

644554044 is a wasteful number, since it uses less digits than its factorization.

644554044 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5968106 (or 5968098 counting only the distinct ones).

The product of its (nonzero) digits is 153600, while the sum is 36.

The square root of 644554044 is about 25388.0689301097. The cubic root of 644554044 is about 863.8130864960.

The spelling of 644554044 in words is "six hundred forty-four million, five hundred fifty-four thousand, forty-four".