61666125864 has 128 divisors (see below), whose sum is σ = 180255559680. Its totient is φ = 17216640000.

The previous prime is 61666125803. The next prime is 61666125869. The reversal of 61666125864 is 46852166616.

It is a happy number.

It is a super-2 number, since 2×61666125864² (a number of 22 digits) contains 22 as substring.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors.

It is not an unprimeable number, because it can be changed into a prime (61666125869) 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 in 31 ways as a sum of consecutive naturals, for example, 1324989 + ... + 1370739.

It is an arithmetic number, because the mean of its divisors is an integer number (1408246560).

Almost surely, 2^61666125864 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 61666125864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (90127779840).

61666125864 is an abundant number, since it is smaller than the sum of its proper divisors (118589433816).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

61666125864 is a wasteful number, since it uses less digits than its factorization.

61666125864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45951 (or 45947 counting only the distinct ones).

The product of its digits is 2488320, while the sum is 51.

The spelling of 61666125864 in words is "sixty-one billion, six hundred sixty-six million, one hundred twenty-five thousand, eight hundred sixty-four".