644000070 has 64 divisors (see below), whose sum is σ = 1772937216. Its totient is φ = 146655360.

The previous prime is 644000053. The next prime is 644000081. The reversal of 644000070 is 70000446.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 52635 + ... + 63705.

It is an arithmetic number, because the mean of its divisors is an integer number (27702144).

Almost surely, 2^644000070 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644000070, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (886468608).

644000070 is an abundant number, since it is smaller than the sum of its proper divisors (1128937146).

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

644000070 is a wasteful number, since it uses less digits than its factorization.

644000070 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11365.

The product of its (nonzero) digits is 672, while the sum is 21.

The square root of 644000070 is about 25377.1564600922. The cubic root of 644000070 is about 863.5655421385.

The spelling of 644000070 in words is "six hundred forty-four million, seventy", and thus it is an aban number.