6501660661 has 8 divisors (see below), whose sum is σ = 6609547448. Its totient is φ = 6393816000.

The previous prime is 6501660653. The next prime is 6501660703. The reversal of 6501660661 is 1660661056.

It can be written as a sum of positive squares in 4 ways, for example, as 463761 + 6501196900 = 681^2 + 80630^2 .

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 6501660661 - 2³ = 6501660653 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 6501660661.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (6501660601) 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, 517231 + ... + 529651.

It is an arithmetic number, because the mean of its divisors is an integer number (826193431).

Almost surely, 2^6501660661 is an apocalyptic number.

6501660661 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

6501660661 is a deficient number, since it is larger than the sum of its proper divisors (107886787).

6501660661 is a wasteful number, since it uses less digits than its factorization.

6501660661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 21063.

The product of its (nonzero) digits is 38880, while the sum is 37.

The square root of 6501660661 is about 80632.8758075762. The cubic root of 6501660661 is about 1866.4144991243.

The spelling of 6501660661 in words is "six billion, five hundred one million, six hundred sixty thousand, six hundred sixty-one".