1561165751 has 2 divisors, whose sum is σ = 1561165752. Its totient is φ = 1561165750.

The previous prime is 1561165717. The next prime is 1561165849. The reversal of 1561165751 is 1575611651.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 1561165751 - 2¹⁸ = 1560903607 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1561125751) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 780582875 + 780582876.

It is an arithmetic number, because the mean of its divisors is an integer number (780582876).

Almost surely, 2^1561165751 is an apocalyptic number.

1561165751 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561165751 is an equidigital number, since it uses as much as digits as its factorization.

1561165751 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31500, while the sum is 38.

The square root of 1561165751 is about 39511.5900844297. The cubic root of 1561165751 is about 1160.0668191296.

The spelling of 1561165751 in words is "one billion, five hundred sixty-one million, one hundred sixty-five thousand, seven hundred fifty-one".