661247911 has 2 divisors, whose sum is σ = 661247912. Its totient is φ = 661247910.

The previous prime is 661247903. The next prime is 661247941. The reversal of 661247911 is 119742166.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 661247911 - 2³ = 661247903 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661247941) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330623955 + 330623956.

It is an arithmetic number, because the mean of its divisors is an integer number (330623956).

Almost surely, 2^661247911 is an apocalyptic number.

661247911 is a deficient number, since it is larger than the sum of its proper divisors (1).

661247911 is an equidigital number, since it uses as much as digits as its factorization.

661247911 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 18144, while the sum is 37.

The square root of 661247911 is about 25714.7411225546. The cubic root of 661247911 is about 871.2071633574.

The spelling of 661247911 in words is "six hundred sixty-one million, two hundred forty-seven thousand, nine hundred eleven".