6501661643 has 4 divisors (see below), whose sum is σ = 6784342608. Its totient is φ = 6218980680.

The previous prime is 6501661613. The next prime is 6501661667. The reversal of 6501661643 is 3461661056.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 6501661643 - 2¹⁰ = 6501660619 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 6501661597 and 6501661606.

It is not an unprimeable number, because it can be changed into a prime (6501661603) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 141340448 + ... + 141340493.

It is an arithmetic number, because the mean of its divisors is an integer number (1696085652).

Almost surely, 2^6501661643 is an apocalyptic number.

6501661643 is a deficient number, since it is larger than the sum of its proper divisors (282680965).

6501661643 is a wasteful number, since it uses less digits than its factorization.

6501661643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 282680964.

The product of its (nonzero) digits is 77760, while the sum is 38.

The square root of 6501661643 is about 80632.8818969036. The cubic root of 6501661643 is about 1866.4145930911.

The spelling of 6501661643 in words is "six billion, five hundred one million, six hundred sixty-one thousand, six hundred forty-three".