661742941 has 2 divisors, whose sum is σ = 661742942. Its totient is φ = 661742940.

The previous prime is 661742927. The next prime is 661743007. The reversal of 661742941 is 149247166.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 397842916 + 263900025 = 19946^2 + 16245^2 .

It is a cyclic number.

It is not a de Polignac number, because 661742941 - 2⁹ = 661742429 is a prime.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 661742894 and 661742903.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661742141) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330871470 + 330871471.

It is an arithmetic number, because the mean of its divisors is an integer number (330871471).

Almost surely, 2^661742941 is an apocalyptic number.

It is an amenable number.

661742941 is a deficient number, since it is larger than the sum of its proper divisors (1).

661742941 is an equidigital number, since it uses as much as digits as its factorization.

661742941 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72576, while the sum is 40.

The square root of 661742941 is about 25724.3647346246. The cubic root of 661742941 is about 871.4245130575.

The spelling of 661742941 in words is "six hundred sixty-one million, seven hundred forty-two thousand, nine hundred forty-one".