1561220663 has 2 divisors, whose sum is σ = 1561220664. Its totient is φ = 1561220662.

The previous prime is 1561220603. The next prime is 1561220677. The reversal of 1561220663 is 3660221651.

It is a strong prime.

It is an emirp because it is prime and its reverse (3660221651) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 1561220663 - 2⁶ = 1561220599 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1561220603) 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, 780610331 + 780610332.

It is an arithmetic number, because the mean of its divisors is an integer number (780610332).

Almost surely, 2^1561220663 is an apocalyptic number.

1561220663 is a deficient number, since it is larger than the sum of its proper divisors (1).

1561220663 is an equidigital number, since it uses as much as digits as its factorization.

1561220663 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 12960, while the sum is 32.

The square root of 1561220663 is about 39512.2849630340. The cubic root of 1561220663 is about 1160.0804202569.

The spelling of 1561220663 in words is "one billion, five hundred sixty-one million, two hundred twenty thousand, six hundred sixty-three".