644100100 has 54 divisors (see below), whose sum is σ = 1625905050. Its totient is φ = 220832640.

The previous prime is 644100071. The next prime is 644100101. The reversal of 644100100 is 1001446.

It is a happy number.

It can be written as a sum of positive squares in 3 ways, for example, as 161594944 + 482505156 = 12712^2 + 21966^2 .

It is not an unprimeable number, because it can be changed into a prime (644100101) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 60825 + ... + 70624.

Almost surely, 2^644100100 is an apocalyptic number.

It is an amenable number.

644100100 is an abundant number, since it is smaller than the sum of its proper divisors (981804950).

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

644100100 is a wasteful number, since it uses less digits than its factorization.

644100100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 131477 (or 131463 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 16.

The square root of 644100100 is about 25379.1272505577. The cubic root of 644100100 is about 863.6102512377.

Adding to 644100100 its reverse (1001446), we get a palindrome (645101546).

The spelling of 644100100 in words is "six hundred forty-four million, one hundred thousand, one hundred".