661961717 has 2 divisors, whose sum is σ = 661961718. Its totient is φ = 661961716.

The previous prime is 661961711. The next prime is 661961747. The reversal of 661961717 is 717169166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 661569841 + 391876 = 25721^2 + 626^2 .

It is a cyclic number.

It is not a de Polignac number, because 661961717 - 2⁴ = 661961701 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661961711) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330980858 + 330980859.

It is an arithmetic number, because the mean of its divisors is an integer number (330980859).

Almost surely, 2^661961717 is an apocalyptic number.

It is an amenable number.

661961717 is a deficient number, since it is larger than the sum of its proper divisors (1).

661961717 is an equidigital number, since it uses as much as digits as its factorization.

661961717 is an evil number, because the sum of its binary digits is even.

The product of its digits is 95256, while the sum is 44.

The square root of 661961717 is about 25728.6166942570. The cubic root of 661961717 is about 871.5205351186.

The spelling of 661961717 in words is "six hundred sixty-one million, nine hundred sixty-one thousand, seven hundred seventeen".