661543079 has 2 divisors, whose sum is σ = 661543080. Its totient is φ = 661543078.

The previous prime is 661543061. The next prime is 661543087. The reversal of 661543079 is 970345166.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 661543079 - 2²⁰ = 660494503 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (661543039) 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, 330771539 + 330771540.

It is an arithmetic number, because the mean of its divisors is an integer number (330771540).

Almost surely, 2^661543079 is an apocalyptic number.

661543079 is a deficient number, since it is larger than the sum of its proper divisors (1).

661543079 is an equidigital number, since it uses as much as digits as its factorization.

661543079 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 136080, while the sum is 41.

The square root of 661543079 is about 25720.4797583560. The cubic root of 661543079 is about 871.3367739611.

It can be divided in two parts, 6615 and 43079, that added together give a palindrome (49694).

The spelling of 661543079 in words is "six hundred sixty-one million, five hundred forty-three thousand, seventy-nine".