643986867 has 8 divisors (see below), whose sum is σ = 895981824. Its totient is φ = 410658248.

The previous prime is 643986859. The next prime is 643986881. The reversal of 643986867 is 768689346.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 643986867 - 2³ = 643986859 is a prime.

It is not an unprimeable number, because it can be changed into a prime (643986857) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4666503 + ... + 4666640.

It is an arithmetic number, because the mean of its divisors is an integer number (111997728).

Almost surely, 2^643986867 is an apocalyptic number.

643986867 is a deficient number, since it is larger than the sum of its proper divisors (251994957).

643986867 is a wasteful number, since it uses less digits than its factorization.

643986867 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9333169.

The product of its digits is 10450944, while the sum is 57.

The square root of 643986867 is about 25376.8963232307. The cubic root of 643986867 is about 863.5596406206.

The spelling of 643986867 in words is "six hundred forty-three million, nine hundred eighty-six thousand, eight hundred sixty-seven".