1631305561 has 2 divisors, whose sum is σ = 1631305562. Its totient is φ = 1631305560.

The previous prime is 1631305549. The next prime is 1631305579. The reversal of 1631305561 is 1655031361.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1627638336 + 3667225 = 40344^2 + 1915^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1631305561 is a prime.

It is a super-2 number, since 2×1631305561² = 5322315666699049442, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (1631305531) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 815652780 + 815652781.

It is an arithmetic number, because the mean of its divisors is an integer number (815652781).

Almost surely, 2^1631305561 is an apocalyptic number.

It is an amenable number.

1631305561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1631305561 is an equidigital number, since it uses as much as digits as its factorization.

1631305561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8100, while the sum is 31.

The square root of 1631305561 is about 40389.4238755643. The cubic root of 1631305561 is about 1177.1860462447.

The spelling of 1631305561 in words is "one billion, six hundred thirty-one million, three hundred five thousand, five hundred sixty-one".