643950649 has 8 divisors (see below), whose sum is σ = 653214528. Its totient is φ = 634743600.

The previous prime is 643950611. The next prime is 643950653. The reversal of 643950649 is 946059346.

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 643950649 - 2¹³ = 643942457 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 643950599 and 643950608.

It is not an unprimeable number, because it can be changed into a prime (643950449) 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, 8884 + ... + 36970.

It is an arithmetic number, because the mean of its divisors is an integer number (81651816).

Almost surely, 2^643950649 is an apocalyptic number.

It is an amenable number.

643950649 is a deficient number, since it is larger than the sum of its proper divisors (9263879).

643950649 is a wasteful number, since it uses less digits than its factorization.

643950649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28415.

The product of its (nonzero) digits is 699840, while the sum is 46.

The square root of 643950649 is about 25376.1827113536. The cubic root of 643950649 is about 863.5434513725.

The spelling of 643950649 in words is "six hundred forty-three million, nine hundred fifty thousand, six hundred forty-nine".