61511111056561 has 2 divisors, whose sum is σ = 61511111056562. Its totient is φ = 61511111056560.

The previous prime is 61511111056553. The next prime is 61511111056663. The reversal of 61511111056561 is 16565011111516.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 50237532568336 + 11273578488225 = 7087844^2 + 3357615^2 .

It is a cyclic number.

It is not a de Polignac number, because 61511111056561 - 2³ = 61511111056553 is a prime.

It is a super-2 number, since 2×61511111056561² (a number of 28 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (61511111056531) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30755555528280 + 30755555528281.

It is an arithmetic number, because the mean of its divisors is an integer number (30755555528281).

Almost surely, 2^{61511111056561} is an apocalyptic number.

It is an amenable number.

61511111056561 is a deficient number, since it is larger than the sum of its proper divisors (1).

61511111056561 is an equidigital number, since it uses as much as digits as its factorization.

61511111056561 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 27000, while the sum is 40.

The spelling of 61511111056561 in words is "sixty-one trillion, five hundred eleven billion, one hundred eleven million, fifty-six thousand, five hundred sixty-one".