2660521561 has 2 divisors, whose sum is σ = 2660521562. Its totient is φ = 2660521560.

The previous prime is 2660521553. The next prime is 2660521609. The reversal of 2660521561 is 1651250662.

2660521561 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 2572518400 + 88003161 = 50720^2 + 9381^2 .

It is a cyclic number.

It is not a de Polignac number, because 2660521561 - 2³ = 2660521553 is a prime.

It is not a weakly prime, because it can be changed into another prime (2660521261) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1330260780 + 1330260781.

It is an arithmetic number, because the mean of its divisors is an integer number (1330260781).

Almost surely, 2^2660521561 is an apocalyptic number.

It is an amenable number.

2660521561 is a deficient number, since it is larger than the sum of its proper divisors (1).

2660521561 is an equidigital number, since it uses as much as digits as its factorization.

2660521561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 21600, while the sum is 34.

The square root of 2660521561 is about 51580.2439020988. The cubic root of 2660521561 is about 1385.6565348615.

The spelling of 2660521561 in words is "two billion, six hundred sixty million, five hundred twenty-one thousand, five hundred sixty-one".