61666727881 has 8 divisors (see below), whose sum is σ = 68194340064. Its totient is φ = 55292706720.

The previous prime is 61666727879. The next prime is 61666727917. The reversal of 61666727881 is 18872766616.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 61666727881 - 2¹ = 61666727879 is a prime.

It is a super-2 number, since 2×61666727881² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (61666727821) 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 in 7 ways as a sum of consecutive naturals, for example, 38396911 + ... + 38398516.

It is an arithmetic number, because the mean of its divisors is an integer number (8524292508).

Almost surely, 2^61666727881 is an apocalyptic number.

It is an amenable number.

61666727881 is a deficient number, since it is larger than the sum of its proper divisors (6527612183).

61666727881 is a wasteful number, since it uses less digits than its factorization.

61666727881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 76795511.

The product of its digits is 8128512, while the sum is 58.

The spelling of 61666727881 in words is "sixty-one billion, six hundred sixty-six million, seven hundred twenty-seven thousand, eight hundred eighty-one".