644406554463364 has 96 divisors (see below), whose sum is σ = 1418905780427520. Its totient is φ = 248759039347200.

The previous prime is 644406554463271. The next prime is 644406554463367. The reversal of 644406554463364 is 463364455604446.

It is a junction number, because it is equal to n+sod(n) for n = 644406554463296 and 644406554463305.

It is not an unprimeable number, because it can be changed into a prime (644406554463367) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1926764874 + ... + 1927099294.

It is an arithmetic number, because the mean of its divisors is an integer number (14780268546120).

Almost surely, 2^{644406554463364} 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 644406554463364, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (709452890213760).

644406554463364 is an abundant number, since it is smaller than the sum of its proper divisors (774499225964156).

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

644406554463364 is a wasteful number, since it uses less digits than its factorization.

644406554463364 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 391949 (or 391947 counting only the distinct ones).

The product of its (nonzero) digits is 1194393600, while the sum is 64.

The spelling of 644406554463364 in words is "six hundred forty-four trillion, four hundred six billion, five hundred fifty-four million, four hundred sixty-three thousand, three hundred sixty-four".