644010004661 has 8 divisors (see below), whose sum is σ = 646642035648. Its totient is φ = 641378500000.

The previous prime is 644010004643. The next prime is 644010004681. The reversal of 644010004661 is 166400010446.

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

It is a cyclic number.

It is not a de Polignac number, because 644010004661 - 2⁶ = 644010004597 is a prime.

It is a super-2 number, since 2×644010004661² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644010004681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2421521 + ... + 2674281.

It is an arithmetic number, because the mean of its divisors is an integer number (80830254456).

Almost surely, 2^644010004661 is an apocalyptic number.

It is an amenable number.

644010004661 is a deficient number, since it is larger than the sum of its proper divisors (2632030987).

644010004661 is a wasteful number, since it uses less digits than its factorization.

644010004661 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 263163.

The product of its (nonzero) digits is 13824, while the sum is 32.

The spelling of 644010004661 in words is "six hundred forty-four billion, ten million, four thousand, six hundred sixty-one".