661612643 has 2 divisors, whose sum is σ = 661612644. Its totient is φ = 661612642.

The previous prime is 661612619. The next prime is 661612667. The reversal of 661612643 is 346216166.

It is a balanced prime because it is at equal distance from previous prime (661612619) and next prime (661612667).

It is a cyclic number.

It is not a de Polignac number, because 661612643 - 2⁸ = 661612387 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (661612603) 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, 330806321 + 330806322.

It is an arithmetic number, because the mean of its divisors is an integer number (330806322).

Almost surely, 2^661612643 is an apocalyptic number.

661612643 is a deficient number, since it is larger than the sum of its proper divisors (1).

661612643 is an equidigital number, since it uses as much as digits as its factorization.

661612643 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 31104, while the sum is 35.

The square root of 661612643 is about 25721.8320303978. The cubic root of 661612643 is about 871.3673144499.

The spelling of 661612643 in words is "six hundred sixty-one million, six hundred twelve thousand, six hundred forty-three".