2105171521 has 2 divisors, whose sum is σ = 2105171522. Its totient is φ = 2105171520.

The previous prime is 2105171491. The next prime is 2105171561. The reversal of 2105171521 is 1251715012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1968164496 + 137007025 = 44364^2 + 11705^2 .

It is a cyclic number.

It is not a de Polignac number, because 2105171521 - 2⁹ = 2105171009 is a prime.

It is not a weakly prime, because it can be changed into another prime (2105171561) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1052585760 + 1052585761.

It is an arithmetic number, because the mean of its divisors is an integer number (1052585761).

Almost surely, 2^2105171521 is an apocalyptic number.

It is an amenable number.

2105171521 is a deficient number, since it is larger than the sum of its proper divisors (1).

2105171521 is an equidigital number, since it uses as much as digits as its factorization.

2105171521 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 700, while the sum is 25.

The square root of 2105171521 is about 45882.1481733364. The cubic root of 2105171521 is about 1281.6295004131.

Adding to 2105171521 its reverse (1251715012), we get a palindrome (3356886533).

The spelling of 2105171521 in words is "two billion, one hundred five million, one hundred seventy-one thousand, five hundred twenty-one".