1561547551 has 2 divisors, whose sum is σ = 1561547552. Its totient is φ = 1561547550.

The previous prime is 1561547503. The next prime is 1561547569. The reversal of 1561547551 is 1557451651.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 1561547551 - 2¹⁹ = 1561023263 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1561541551) 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, 780773775 + 780773776.

It is an arithmetic number, because the mean of its divisors is an integer number (780773776).

Almost surely, 2^1561547551 is an apocalyptic number.

1561547551 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561547551 is an equidigital number, since it uses as much as digits as its factorization.

1561547551 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 105000, while the sum is 40.

The square root of 1561547551 is about 39516.4212828034. The cubic root of 1561547551 is about 1160.1613803914.

The spelling of 1561547551 in words is "one billion, five hundred sixty-one million, five hundred forty-seven thousand, five hundred fifty-one".