644136126 has 32 divisors (see below), whose sum is σ = 1301250048. Its totient is φ = 212556960.

The previous prime is 644136121. The next prime is 644136161. The reversal of 644136126 is 621631446.

It is a super-2 number, since 2×644136126² = 829822697636575752, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644136121) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 649491 + ... + 650481.

It is an arithmetic number, because the mean of its divisors is an integer number (40664064).

Almost surely, 2^644136126 is an apocalyptic number.

644136126 is an abundant number, since it is smaller than the sum of its proper divisors (657113922).

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

644136126 is a wasteful number, since it uses less digits than its factorization.

644136126 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1976.

The product of its digits is 20736, while the sum is 33.

The square root of 644136126 is about 25379.8369971125. The cubic root of 644136126 is about 863.6263521734.

The spelling of 644136126 in words is "six hundred forty-four million, one hundred thirty-six thousand, one hundred twenty-six".