644400460446 has 32 divisors (see below), whose sum is σ = 1376688983328. Its totient is φ = 200375777280.

The previous prime is 644400460397. The next prime is 644400460447. The reversal of 644400460446 is 644064004446.

It is a junction number, because it is equal to n+sod(n) for n = 644400460398 and 644400460407.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644400460447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27942685 + ... + 27965736.

It is an arithmetic number, because the mean of its divisors is an integer number (43021530729).

Almost surely, 2^644400460446 is an apocalyptic number.

644400460446 is an abundant number, since it is smaller than the sum of its proper divisors (732288522882).

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

644400460446 is a wasteful number, since it uses less digits than its factorization.

644400460446 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 55908556.

The product of its (nonzero) digits is 884736, while the sum is 42.

The spelling of 644400460446 in words is "six hundred forty-four billion, four hundred million, four hundred sixty thousand, four hundred forty-six".