644294400 has 216 divisors, whose sum is σ = 2220274560. Its totient is φ = 164229120.

The previous prime is 644294381. The next prime is 644294411. The reversal of 644294400 is 4492446.

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, 440871 + ... + 442329.

Almost surely, 2^644294400 is an apocalyptic number.

644294400 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 644294400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1110137280).

644294400 is an abundant number, since it is smaller than the sum of its proper divisors (1575980160).

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

644294400 is a wasteful number, since it uses less digits than its factorization.

644294400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1511 (or 1492 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 33.

The square root of 644294400 is about 25382.9549107270. The cubic root of 644294400 is about 863.6970817380.

The spelling of 644294400 in words is "six hundred forty-four million, two hundred ninety-four thousand, four hundred".