661606342541 has 2 divisors, whose sum is σ = 661606342542. Its totient is φ = 661606342540.

The previous prime is 661606342487. The next prime is 661606342549. The reversal of 661606342541 is 145243606166.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 400209329641 + 261397012900 = 632621^2 + 511270^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-661606342541 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 661606342492 and 661606342501.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661606342549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330803171270 + 330803171271.

It is an arithmetic number, because the mean of its divisors is an integer number (330803171271).

Almost surely, 2^661606342541 is an apocalyptic number.

It is an amenable number.

661606342541 is a deficient number, since it is larger than the sum of its proper divisors (1).

661606342541 is an equidigital number, since it uses as much as digits as its factorization.

661606342541 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 622080, while the sum is 44.

The spelling of 661606342541 in words is "six hundred sixty-one billion, six hundred six million, three hundred forty-two thousand, five hundred forty-one".