644270465521 has 8 divisors (see below), whose sum is σ = 666506998080. Its totient is φ = 622035286992.

The previous prime is 644270465519. The next prime is 644270465551. The reversal of 644270465521 is 125564072446.

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 644270465521 - 2¹ = 644270465519 is a prime.

It is a super-5 number, since 5×644270465521⁵ (a number of 60 digits) contains 55555 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (644270465551) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 681706 + ... + 1324108.

It is an arithmetic number, because the mean of its divisors is an integer number (83313374760).

Almost surely, 2^644270465521 is an apocalyptic number.

It is an amenable number.

644270465521 is a deficient number, since it is larger than the sum of its proper divisors (22236532559).

644270465521 is a wasteful number, since it uses less digits than its factorization.

644270465521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 677015.

The product of its (nonzero) digits is 1612800, while the sum is 46.

The spelling of 644270465521 in words is "six hundred forty-four billion, two hundred seventy million, four hundred sixty-five thousand, five hundred twenty-one".