644814378 has 32 divisors (see below), whose sum is σ = 1543147200. Its totient is φ = 198404208.

The previous prime is 644814367. The next prime is 644814389. The reversal of 644814378 is 873418446.

644814378 is a `hidden beast` number, since 64 + 481 + 43 + 78 = 666.

644814378 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is an interprime number because it is at equal distance from previous prime (644814367) and next prime (644814389).

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 458568 + ... + 459971.

It is an arithmetic number, because the mean of its divisors is an integer number (48223350).

Almost surely, 2^644814378 is an apocalyptic number.

644814378 is an abundant number, since it is smaller than the sum of its proper divisors (898332822).

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

644814378 is a wasteful number, since it uses less digits than its factorization.

644814378 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 918563 (or 918557 counting only the distinct ones).

The product of its digits is 516096, while the sum is 45.

The square root of 644814378 is about 25393.1955058831. The cubic root of 644814378 is about 863.9293682615.

The spelling of 644814378 in words is "six hundred forty-four million, eight hundred fourteen thousand, three hundred seventy-eight".