643246021 has 8 divisors (see below), whose sum is σ = 708537024. Its totient is φ = 579090720.

The previous prime is 643246003. The next prime is 643246027. The reversal of 643246021 is 120642346.

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

It is not a de Polignac number, because 643246021 - 2⁵ = 643245989 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (643246027) 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, 282736 + ... + 285001.

It is an arithmetic number, because the mean of its divisors is an integer number (88567128).

Almost surely, 2^643246021 is an apocalyptic number.

It is an amenable number.

643246021 is a deficient number, since it is larger than the sum of its proper divisors (65291003).

643246021 is a wasteful number, since it uses less digits than its factorization.

643246021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 567851.

The product of its (nonzero) digits is 6912, while the sum is 28.

The square root of 643246021 is about 25362.2952628503. The cubic root of 643246021 is about 863.2283656496.

Adding to 643246021 its reverse (120642346), we get a palindrome (763888367).

The spelling of 643246021 in words is "six hundred forty-three million, two hundred forty-six thousand, twenty-one".