644242446 has 48 divisors (see below), whose sum is σ = 1436520384. Its totient is φ = 208516032.

The previous prime is 644242381. The next prime is 644242451.

644242446 is a `hidden beast` number, since 644 + 2 + 4 + 2 + 4 + 4 + 6 = 666.

644242446 is nontrivially palindromic in base 10.

It is a self number, because there is not a number n which added to its sum of digits gives 644242446.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 583531 + ... + 584633.

It is an arithmetic number, because the mean of its divisors is an integer number (29927508).

Almost surely, 2^644242446 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644242446, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (718260192).

644242446 is an abundant number, since it is smaller than the sum of its proper divisors (792277938).

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

644242446 is a wasteful number, since it uses less digits than its factorization.

644242446 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2025 (or 2022 counting only the distinct ones).

The product of its digits is 147456, while the sum is 36.

The square root of 644242446 is about 25381.9314867880. The cubic root of 644242446 is about 863.6738657856.

The spelling of 644242446 in words is "six hundred forty-four million, two hundred forty-two thousand, four hundred forty-six".