1561172017 has 2 divisors, whose sum is σ = 1561172018. Its totient is φ = 1561172016.

The previous prime is 1561172003. The next prime is 1561172021. The reversal of 1561172017 is 7102711651.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1483097121 + 78074896 = 38511^2 + 8836^2 .

It is a cyclic number.

It is not a de Polignac number, because 1561172017 - 2¹¹ = 1561169969 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 1561172017.

It is not a weakly prime, because it can be changed into another prime (1561172027) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 780586008 + 780586009.

It is an arithmetic number, because the mean of its divisors is an integer number (780586009).

Almost surely, 2^1561172017 is an apocalyptic number.

It is an amenable number.

1561172017 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561172017 is an equidigital number, since it uses as much as digits as its factorization.

1561172017 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2940, while the sum is 31.

The square root of 1561172017 is about 39511.6693775396. The cubic root of 1561172017 is about 1160.0683711683.

Adding to 1561172017 its reverse (7102711651), we get a palindrome (8663883668).

The spelling of 1561172017 in words is "one billion, five hundred sixty-one million, one hundred seventy-two thousand, seventeen".