661612543 has 2 divisors, whose sum is σ = 661612544. Its totient is φ = 661612542.

The previous prime is 661612541. The next prime is 661612559. The reversal of 661612543 is 345216166.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 661612543 - 2¹ = 661612541 is a prime.

Together with 661612541, it forms a pair of twin primes.

It is a junction number, because it is equal to n+sod(n) for n = 661612499 and 661612508.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661612541) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 330806271 + 330806272.

It is an arithmetic number, because the mean of its divisors is an integer number (330806272).

Almost surely, 2^661612543 is an apocalyptic number.

661612543 is a deficient number, since it is larger than the sum of its proper divisors (1).

661612543 is an equidigital number, since it uses as much as digits as its factorization.

661612543 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 25920, while the sum is 34.

The square root of 661612543 is about 25721.8300865238. The cubic root of 661612543 is about 871.3672705487.

The spelling of 661612543 in words is "six hundred sixty-one million, six hundred twelve thousand, five hundred forty-three".