643660406 has 8 divisors (see below), whose sum is σ = 967973760. Its totient is φ = 321002488.

The previous prime is 643660393. The next prime is 643660411. The reversal of 643660406 is 604066346.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 412886 + ... + 414441.

It is an arithmetic number, because the mean of its divisors is an integer number (120996720).

Almost surely, 2^643660406 is an apocalyptic number.

643660406 is a deficient number, since it is larger than the sum of its proper divisors (324313354).

643660406 is a wasteful number, since it uses less digits than its factorization.

643660406 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 827718.

The product of its (nonzero) digits is 62208, while the sum is 35.

The square root of 643660406 is about 25370.4632594677. The cubic root of 643660406 is about 863.4136924085.

The spelling of 643660406 in words is "six hundred forty-three million, six hundred sixty thousand, four hundred six".