2605661521 has 2 divisors, whose sum is σ = 2605661522. Its totient is φ = 2605661520.

The previous prime is 2605661491. The next prime is 2605661533. The reversal of 2605661521 is 1251665062.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2476157121 + 129504400 = 49761^2 + 11380^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2605661521 is a prime.

It is not a weakly prime, because it can be changed into another prime (2605661221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1302830760 + 1302830761.

It is an arithmetic number, because the mean of its divisors is an integer number (1302830761).

Almost surely, 2^2605661521 is an apocalyptic number.

It is an amenable number.

2605661521 is a deficient number, since it is larger than the sum of its proper divisors (1).

2605661521 is an equidigital number, since it uses as much as digits as its factorization.

2605661521 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 2605661521 is about 51045.6807281478. The cubic root of 2605661521 is about 1376.0662180323.

The spelling of 2605661521 in words is "two billion, six hundred five million, six hundred sixty-one thousand, five hundred twenty-one".