20992111042561 has 2 divisors, whose sum is σ = 20992111042562. Its totient is φ = 20992111042560.

The previous prime is 20992111042549. The next prime is 20992111042603. The reversal of 20992111042561 is 16524011129902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16443381841936 + 4548729200625 = 4055044^2 + 2132775^2 .

It is a cyclic number.

It is not a de Polignac number, because 20992111042561 - 2⁷ = 20992111042433 is a prime.

It is a super-2 number, since 2×20992111042561² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (20992111042501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10496055521280 + 10496055521281.

It is an arithmetic number, because the mean of its divisors is an integer number (10496055521281).

Almost surely, 2^{20992111042561} is an apocalyptic number.

It is an amenable number.

20992111042561 is a deficient number, since it is larger than the sum of its proper divisors (1).

20992111042561 is an equidigital number, since it uses as much as digits as its factorization.

20992111042561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 77760, while the sum is 43.

The spelling of 20992111042561 in words is "twenty trillion, nine hundred ninety-two billion, one hundred eleven million, forty-two thousand, five hundred sixty-one".