661417121 has 2 divisors, whose sum is σ = 661417122. Its totient is φ = 661417120.

The previous prime is 661417103. The next prime is 661417139. The reversal of 661417121 is 121714166.

661417121 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a balanced prime because it is at equal distance from previous prime (661417103) and next prime (661417139).

It can be written as a sum of positive squares in only one way, i.e., 509856400 + 151560721 = 22580^2 + 12311^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661417121 is a prime.

It is not a weakly prime, because it can be changed into another prime (661417171) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330708560 + 330708561.

It is an arithmetic number, because the mean of its divisors is an integer number (330708561).

Almost surely, 2^661417121 is an apocalyptic number.

It is an amenable number.

661417121 is a deficient number, since it is larger than the sum of its proper divisors (1).

661417121 is an equidigital number, since it uses as much as digits as its factorization.

661417121 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2016, while the sum is 29.

The square root of 661417121 is about 25718.0310482743. The cubic root of 661417121 is about 871.2814695236.

The spelling of 661417121 in words is "six hundred sixty-one million, four hundred seventeen thousand, one hundred twenty-one".