644453225553545 has 16 divisors (see below), whose sum is σ = 790739304628752. Its totient is φ = 504034860026880.

The previous prime is 644453225553509. The next prime is 644453225553559. The reversal of 644453225553545 is 545355522354446.

It can be written as a sum of positive squares in 8 ways, for example, as 28105223662096 + 616348001891449 = 5301436^2 + 24826357^2 .

It is not a de Polignac number, because 644453225553545 - 2¹⁸ = 644453225291401 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4327147892 + ... + 4327296821.

It is an arithmetic number, because the mean of its divisors is an integer number (49421206539297).

Almost surely, 2^{644453225553545} is an apocalyptic number.

It is an amenable number.

644453225553545 is a deficient number, since it is larger than the sum of its proper divisors (146286079075207).

644453225553545 is a wasteful number, since it uses less digits than its factorization.

644453225553545 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8654445052.

The product of its digits is 864000000, while the sum is 62.

The spelling of 644453225553545 in words is "six hundred forty-four trillion, four hundred fifty-three billion, two hundred twenty-five million, five hundred fifty-three thousand, five hundred forty-five".