644543104 has 16 divisors (see below), whose sum is σ = 1284050970. Its totient is φ = 322271488.

The previous prime is 644543089. The next prime is 644543113. The reversal of 644543104 is 401345446.

It can be written as a sum of positive squares in only one way, i.e., 547560000 + 96983104 = 23400^2 + 9848^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is a hoax number, since the sum of its digits (31) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 2517619 + ... + 2517874.

Almost surely, 2^644543104 is an apocalyptic number.

644543104 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

644543104 is a deficient number, since it is larger than the sum of its proper divisors (639507866).

644543104 is an equidigital number, since it uses as much as digits as its factorization.

644543104 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5035507 (or 5035495 counting only the distinct ones).

The product of its (nonzero) digits is 23040, while the sum is 31.

The square root of 644543104 is about 25387.8534736594. The cubic root of 644543104 is about 863.8081993089.

The spelling of 644543104 in words is "six hundred forty-four million, five hundred forty-three thousand, one hundred four".