644807076221952 has 704 divisors, whose sum is σ = 2367145554439680. Its totient is φ = 169164354355200.

The previous prime is 644807076221927. The next prime is 644807076222079. The reversal of 644807076221952 is 259122670708446.

644807076221952 is a `hidden beast` number, since 6 + 4 + 480 + 7 + 0 + 7 + 62 + 2 + 1 + 95 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (63).

It is a self number, because there is not a number n which added to its sum of digits gives 644807076221952.

It is a congruent number.

It is an unprimeable number.

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 63 ways as a sum of consecutive naturals, for example, 132504552 + ... + 137284632.

Almost surely, 2^{644807076221952} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644807076221952, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1183572777219840).

644807076221952 is an abundant number, since it is smaller than the sum of its proper divisors (1722338478217728).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

644807076221952 is a wasteful number, since it uses less digits than its factorization.

644807076221952 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4780175 (or 4780151 counting only the distinct ones).

The product of its (nonzero) digits is 81285120, while the sum is 63.

The spelling of 644807076221952 in words is "six hundred forty-four trillion, eight hundred seven billion, seventy-six million, two hundred twenty-one thousand, nine hundred fifty-two".