6661660509 has 32 divisors (see below), whose sum is σ = 11872640000. Its totient is φ = 3606310512.

The previous prime is 6661660429. The next prime is 6661660513. The reversal of 6661660509 is 9050661666.

It is not a de Polignac number, because 6661660509 - 2⁷ = 6661660381 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 (6661660549) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 923959 + ... + 931140.

It is an arithmetic number, because the mean of its divisors is an integer number (371020000).

Almost surely, 2^6661660509 is an apocalyptic number.

It is an amenable number.

6661660509 is a deficient number, since it is larger than the sum of its proper divisors (5210979491).

6661660509 is a wasteful number, since it uses less digits than its factorization.

6661660509 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1855134 (or 1855128 counting only the distinct ones).

The product of its (nonzero) digits is 349920, while the sum is 45.

The square root of 6661660509 is about 81618.9960058319. The cubic root of 6661660509 is about 1881.6008423204.

The spelling of 6661660509 in words is "six billion, six hundred sixty-one million, six hundred sixty thousand, five hundred nine".