644166100 has 36 divisors (see below), whose sum is σ = 1420769308. Its totient is φ = 253440000.

The previous prime is 644166097. The next prime is 644166109. The reversal of 644166100 is 1661446.

It can be written as a sum of positive squares in 6 ways, for example, as 10536516 + 633629584 = 3246^2 + 25172^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (644166109) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 46701 + ... + 58900.

Almost surely, 2^644166100 is an apocalyptic number.

It is an amenable number.

644166100 is an abundant number, since it is smaller than the sum of its proper divisors (776603208).

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

644166100 is a wasteful number, since it uses less digits than its factorization.

644166100 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 105676 (or 105669 counting only the distinct ones).

The product of its (nonzero) digits is 3456, while the sum is 28.

The square root of 644166100 is about 25380.4274983697. The cubic root of 644166100 is about 863.6397478588.

The spelling of 644166100 in words is "six hundred forty-four million, one hundred sixty-six thousand, one hundred".