643720550 has 96 divisors (see below), whose sum is σ = 1376054784. Its totient is φ = 221760000.

The previous prime is 643720547. The next prime is 643720559. The reversal of 643720550 is 55027346.

It is a super-2 number, since 2×643720550² = 828752292984605000, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643720559) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 1909982 + ... + 1910318.

It is an arithmetic number, because the mean of its divisors is an integer number (14333904).

Almost surely, 2^643720550 is an apocalyptic number.

643720550 is an abundant number, since it is smaller than the sum of its proper divisors (732334234).

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

643720550 is a wasteful number, since it uses less digits than its factorization.

643720550 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 534 (or 529 counting only the distinct ones).

The product of its (nonzero) digits is 25200, while the sum is 32.

The square root of 643720550 is about 25371.6485471481. The cubic root of 643720550 is about 863.4405841956.

Adding to 643720550 its reverse (55027346), we get a palindrome (698747896).

The spelling of 643720550 in words is "six hundred forty-three million, seven hundred twenty thousand, five hundred fifty".