644643450 has 144 divisors (see below), whose sum is σ = 1950803712. Its totient is φ = 151200000.

The previous prime is 644643437. The next prime is 644643463. The reversal of 644643450 is 54346446.

644643450 is a `hidden beast` number, since 6 + 4 + 4 + 643 + 4 + 5 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (644643437) and next prime (644643463).

It is an unprimeable number.

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 71 ways as a sum of consecutive naturals, for example, 151350 + ... + 155550.

It is an arithmetic number, because the mean of its divisors is an integer number (13547248).

Almost surely, 2^644643450 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644643450, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (975401856).

644643450 is an abundant number, since it is smaller than the sum of its proper divisors (1306160262).

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

644643450 is a wasteful number, since it uses less digits than its factorization.

644643450 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4261 (or 4253 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 36.

The square root of 644643450 is about 25389.8296567740. The cubic root of 644643450 is about 863.8530244463.

Adding to 644643450 its reverse (54346446), we get a palindrome (698989896).

The spelling of 644643450 in words is "six hundred forty-four million, six hundred forty-three thousand, four hundred fifty".