2105171561 has 2 divisors, whose sum is σ = 2105171562. Its totient is φ = 2105171560.

The previous prime is 2105171521. The next prime is 2105171599. The reversal of 2105171561 is 1651715012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 2037619600 + 67551961 = 45140^2 + 8219^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-2105171561 is a prime.

It is not a weakly prime, because it can be changed into another prime (2105171521) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1052585780 + 1052585781.

It is an arithmetic number, because the mean of its divisors is an integer number (1052585781).

Almost surely, 2^2105171561 is an apocalyptic number.

It is an amenable number.

2105171561 is a deficient number, since it is larger than the sum of its proper divisors (1).

2105171561 is an equidigital number, since it uses as much as digits as its factorization.

2105171561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2100, while the sum is 29.

The square root of 2105171561 is about 45882.1486092358. The cubic root of 2105171561 is about 1281.6295085304.

Adding to 2105171561 its reverse (1651715012), we get a palindrome (3756886573).

The spelling of 2105171561 in words is "two billion, one hundred five million, one hundred seventy-one thousand, five hundred sixty-one".