643355657 has 16 divisors (see below), whose sum is σ = 743097600. Its totient is φ = 545605632.

The previous prime is 643355653. The next prime is 643355663. The reversal of 643355657 is 756553346.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 643355657 - 2² = 643355653 is a prime.

It is not an unprimeable number, because it can be changed into a prime (643355651) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 267653 + ... + 270045.

It is an arithmetic number, because the mean of its divisors is an integer number (46443600).

Almost surely, 2^643355657 is an apocalyptic number.

It is an amenable number.

643355657 is a deficient number, since it is larger than the sum of its proper divisors (99741943).

643355657 is a wasteful number, since it uses less digits than its factorization.

643355657 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2792.

The product of its digits is 1134000, while the sum is 44.

The square root of 643355657 is about 25364.4565681979. The cubic root of 643355657 is about 863.2774062580.

The spelling of 643355657 in words is "six hundred forty-three million, three hundred fifty-five thousand, six hundred fifty-seven".