644814 has 16 divisors (see below), whose sum is σ = 1433040. Its totient is φ = 214920.

The previous prime is 644801. The next prime is 644837. The reversal of 644814 is 418446.

644814 = 400² + 401² + ... + 403².

644814 is a `hidden beast` number, since 644 + 8 + 14 = 666.

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 644814.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5917 + ... + 6024.

It is an arithmetic number, because the mean of its divisors is an integer number (89565).

2⁶⁴⁴⁸¹⁴ is an apocalyptic number.

644814 is an abundant number, since it is smaller than the sum of its proper divisors (788226).

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

644814 is a wasteful number, since it uses less digits than its factorization.

644814 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 11952 (or 11946 counting only the distinct ones).

The product of its digits is 3072, while the sum is 27.

The square root of 644814 is about 803.0031133190. The cubic root of 644814 is about 86.3929199445.

The spelling of 644814 in words is "six hundred forty-four thousand, eight hundred fourteen".