1020111001561 has 2 divisors, whose sum is σ = 1020111001562. Its totient is φ = 1020111001560.

The previous prime is 1020111001549. The next prime is 1020111001577. The reversal of 1020111001561 is 1651001110201.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 966092410000 + 54018591561 = 982900^2 + 232419^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-1020111001561 is a prime.

It is not a weakly prime, because it can be changed into another prime (1020111001061) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 510055500780 + 510055500781.

It is an arithmetic number, because the mean of its divisors is an integer number (510055500781).

Almost surely, 2^{1020111001561} is an apocalyptic number.

It is an amenable number.

1020111001561 is a deficient number, since it is larger than the sum of its proper divisors (1).

1020111001561 is an equidigital number, since it uses as much as digits as its factorization.

1020111001561 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 60, while the sum is 19.

Adding to 1020111001561 its reverse (1651001110201), we get a palindrome (2671112111762).

The spelling of 1020111001561 in words is "one trillion, twenty billion, one hundred eleven million, one thousand, five hundred sixty-one".