1561541873 has 2 divisors, whose sum is σ = 1561541874. Its totient is φ = 1561541872.

The previous prime is 1561541869. The next prime is 1561541881. The reversal of 1561541873 is 3781451651.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1010794849 + 550747024 = 31793^2 + 23468^2 .

It is an emirp because it is prime and its reverse (3781451651) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1561541873 - 2² = 1561541869 is a prime.

It is a super-2 number, since 2×1561541873² = 4876826042264696258, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 1561541873.

It is not a weakly prime, because it can be changed into another prime (1561541803) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 780770936 + 780770937.

It is an arithmetic number, because the mean of its divisors is an integer number (780770937).

Almost surely, 2^1561541873 is an apocalyptic number.

It is an amenable number.

1561541873 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561541873 is an equidigital number, since it uses as much as digits as its factorization.

1561541873 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 100800, while the sum is 41.

The square root of 1561541873 is about 39516.3494391878. The cubic root of 1561541873 is about 1160.1599742213.

The spelling of 1561541873 in words is "one billion, five hundred sixty-one million, five hundred forty-one thousand, eight hundred seventy-three".