643264400 has 60 divisors (see below), whose sum is σ = 1547951892. Its totient is φ = 256888320.

The previous prime is 643264381. The next prime is 643264403. The reversal of 643264400 is 4462346.

It is a happy number.

It can be written as a sum of positive squares in 6 ways, for example, as 9634816 + 633629584 = 3104^2 + 25172^2 .

It is not an unprimeable number, because it can be changed into a prime (643264403) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 397994 + ... + 399606.

Almost surely, 2^643264400 is an apocalyptic number.

It is an amenable number.

643264400 is an abundant number, since it is smaller than the sum of its proper divisors (904687492).

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

643264400 is a wasteful number, since it uses less digits than its factorization.

643264400 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2628 (or 2617 counting only the distinct ones).

The product of its (nonzero) digits is 13824, while the sum is 29.

The square root of 643264400 is about 25362.6575894562. The cubic root of 643264400 is about 863.2365870364.

The spelling of 643264400 in words is "six hundred forty-three million, two hundred sixty-four thousand, four hundred".