644131138 has 8 divisors (see below), whose sum is σ = 1104224832. Its totient is φ = 276056196.

The previous prime is 644131121. The next prime is 644131157. The reversal of 644131138 is 831131446.

It is a sphenic number, since it is the product of 3 distinct primes.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 23004670 + ... + 23004697.

It is an arithmetic number, because the mean of its divisors is an integer number (138028104).

Almost surely, 2^644131138 is an apocalyptic number.

644131138 is a deficient number, since it is larger than the sum of its proper divisors (460093694).

644131138 is a wasteful number, since it uses less digits than its factorization.

644131138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46009376.

The product of its digits is 6912, while the sum is 31.

The square root of 644131138 is about 25379.7387299397. The cubic root of 644131138 is about 863.6241229451.

The spelling of 644131138 in words is "six hundred forty-four million, one hundred thirty-one thousand, one hundred thirty-eight".