643618400 has 36 divisors (see below), whose sum is σ = 1571235372. Its totient is φ = 257447040.

The previous prime is 643618399. The next prime is 643618411. The reversal of 643618400 is 4816346.

It is a Harshad number since it is a multiple of its sum of digits (32).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 401462 + ... + 403061.

It is an arithmetic number, because the mean of its divisors is an integer number (43645427).

Almost surely, 2^643618400 is an apocalyptic number.

It is an amenable number.

643618400 is an abundant number, since it is smaller than the sum of its proper divisors (927616972).

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

643618400 is a wasteful number, since it uses less digits than its factorization.

643618400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 804543 (or 804530 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 32.

The square root of 643618400 is about 25369.6353935172. The cubic root of 643618400 is about 863.3949095512.

The spelling of 643618400 in words is "six hundred forty-three million, six hundred eighteen thousand, four hundred".