644732055917 has 4 divisors (see below), whose sum is σ = 644739132576. Its totient is φ = 644724979260.

The previous prime is 644732055887. The next prime is 644732055943. The reversal of 644732055917 is 719550237446.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 644732055917 - 2¹⁸ = 644731793773 is a prime.

It is a super-2 number, since 2×644732055917² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644732855917) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3399863 + ... + 3584484.

It is an arithmetic number, because the mean of its divisors is an integer number (161184783144).

Almost surely, 2^644732055917 is an apocalyptic number.

It is an amenable number.

644732055917 is a deficient number, since it is larger than the sum of its proper divisors (7076659).

644732055917 is an equidigital number, since it uses as much as digits as its factorization.

644732055917 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7076658.

The product of its (nonzero) digits is 6350400, while the sum is 53.

The spelling of 644732055917 in words is "six hundred forty-four billion, seven hundred thirty-two million, fifty-five thousand, nine hundred seventeen".