644667574753 has 4 divisors (see below), whose sum is σ = 644677063060. Its totient is φ = 644658086448.

The previous prime is 644667574741. The next prime is 644667574757. The reversal of 644667574753 is 357475766446.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 249508242064 + 395159332689 = 499508^2 + 628617^2 .

It is a cyclic number.

It is not a de Polignac number, because 644667574753 - 2³⁷ = 507228621281 is a prime.

It is a super-2 number, since 2×644667574753² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644667574757) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4641498 + ... + 4778371.

It is an arithmetic number, because the mean of its divisors is an integer number (161169265765).

Almost surely, 2^644667574753 is an apocalyptic number.

It is an amenable number.

644667574753 is a deficient number, since it is larger than the sum of its proper divisors (9488307).

644667574753 is an equidigital number, since it uses as much as digits as its factorization.

644667574753 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9488306.

The product of its digits is 355622400, while the sum is 64.

The spelling of 644667574753 in words is "six hundred forty-four billion, six hundred sixty-seven million, five hundred seventy-four thousand, seven hundred fifty-three".