643979941 has 8 divisors (see below), whose sum is σ = 743848704. Its totient is φ = 550998720.

The previous prime is 643979933. The next prime is 643979969. The reversal of 643979941 is 149979346.

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 643979941 - 2³ = 643979933 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 (643979971) 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, 1721685 + ... + 1722058.

It is an arithmetic number, because the mean of its divisors is an integer number (92981088).

Almost surely, 2^643979941 is an apocalyptic number.

It is an amenable number.

643979941 is a deficient number, since it is larger than the sum of its proper divisors (99868763).

643979941 is a wasteful number, since it uses less digits than its factorization.

643979941 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3443771.

The product of its digits is 1469664, while the sum is 52.

The square root of 643979941 is about 25376.7598601555. The cubic root of 643979941 is about 863.5565447834.

The spelling of 643979941 in words is "six hundred forty-three million, nine hundred seventy-nine thousand, nine hundred forty-one".