6661521505 has 16 divisors (see below), whose sum is σ = 8573325120. Its totient is φ = 4953469248.

The previous prime is 6661521481. The next prime is 6661521509. The reversal of 6661521505 is 5051251666.

6661521505 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a cyclic number.

It is not a de Polignac number, because 6661521505 - 2⁹ = 6661520993 is a prime.

It is not an unprimeable number, because it can be changed into a prime (6661521509) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 656487 + ... + 666556.

It is an arithmetic number, because the mean of its divisors is an integer number (535832820).

Almost surely, 2^6661521505 is an apocalyptic number.

It is an amenable number.

6661521505 is a deficient number, since it is larger than the sum of its proper divisors (1911803615).

6661521505 is a wasteful number, since it uses less digits than its factorization.

6661521505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1323120.

The product of its (nonzero) digits is 54000, while the sum is 37.

The square root of 6661521505 is about 81618.1444594276. The cubic root of 6661521505 is about 1881.5877548996.

The spelling of 6661521505 in words is "six billion, six hundred sixty-one million, five hundred twenty-one thousand, five hundred five".