661316647 has 2 divisors, whose sum is σ = 661316648. Its totient is φ = 661316646.

The previous prime is 661316639. The next prime is 661316653. The reversal of 661316647 is 746613166.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661316647 - 2³ = 661316639 is a prime.

It is a super-3 number, since 3×661316647³ (a number of 27 digits) contains 333 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661316627) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330658323 + 330658324.

It is an arithmetic number, because the mean of its divisors is an integer number (330658324).

Almost surely, 2^661316647 is an apocalyptic number.

661316647 is a deficient number, since it is larger than the sum of its proper divisors (1).

661316647 is an equidigital number, since it uses as much as digits as its factorization.

661316647 is an evil number, because the sum of its binary digits is even.

The product of its digits is 108864, while the sum is 40.

The square root of 661316647 is about 25716.0775974875. The cubic root of 661316647 is about 871.2373493234.

The spelling of 661316647 in words is "six hundred sixty-one million, three hundred sixteen thousand, six hundred forty-seven".