644834802553 has 4 divisors (see below), whose sum is σ = 665635925248. Its totient is φ = 624033679860.

The previous prime is 644834802539. The next prime is 644834802559. The reversal of 644834802553 is 355208438446.

644834802553 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

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, and also an emirpimes, since its reverse is a distinct semiprime: 355208438446 = 2 ⋅177604219223.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-644834802553 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 644834802553.

It is not an unprimeable number, because it can be changed into a prime (644834802559) 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, 10400561301 + ... + 10400561362.

It is an arithmetic number, because the mean of its divisors is an integer number (166408981312).

Almost surely, 2^644834802553 is an apocalyptic number.

It is an amenable number.

644834802553 is a deficient number, since it is larger than the sum of its proper divisors (20801122695).

644834802553 is a wasteful number, since it uses less digits than its factorization.

644834802553 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20801122694.

The product of its (nonzero) digits is 11059200, while the sum is 52.

The spelling of 644834802553 in words is "six hundred forty-four billion, eight hundred thirty-four million, eight hundred two thousand, five hundred fifty-three".