61666217659 has 2 divisors, whose sum is σ = 61666217660. Its totient is φ = 61666217658.

The previous prime is 61666217603. The next prime is 61666217737. The reversal of 61666217659 is 95671266616.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 61666217659 - 2⁷ = 61666217531 is a prime.

It is not a weakly prime, because it can be changed into another prime (61666217359) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 30833108829 + 30833108830.

It is an arithmetic number, because the mean of its divisors is an integer number (30833108830).

Almost surely, 2^61666217659 is an apocalyptic number.

61666217659 is a deficient number, since it is larger than the sum of its proper divisors (1).

61666217659 is an equidigital number, since it uses as much as digits as its factorization.

61666217659 is an evil number, because the sum of its binary digits is even.

The product of its digits is 4898880, while the sum is 55.

The spelling of 61666217659 in words is "sixty-one billion, six hundred sixty-six million, two hundred seventeen thousand, six hundred fifty-nine".