66121297038720 has 5376 divisors, whose sum is σ = 316497712426560. Its totient is φ = 13151467929600.

The previous prime is 66121297038707. The next prime is 66121297038749. The reversal of 66121297038720 is 2783079212166.

It is a happy number.

66121297038720 is a `hidden beast` number, since 6 + 612 + 12 + 9 + 7 + 0 + 3 + 8 + 7 + 2 + 0 = 666.

66121297038720 is digitally balanced in base 5, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 671 ways as a sum of consecutive naturals, for example, 1247571642214 + ... + 1247571642266.

Almost surely, 2^{66121297038720} is an apocalyptic number.

66121297038720 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66121297038720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (158248856213280).

66121297038720 is an abundant number, since it is smaller than the sum of its proper divisors (250376415387840).

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

66121297038720 is an equidigital number, since it uses as much as digits as its factorization.

66121297038720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 178 (or 122 counting only the distinct ones).

The product of its (nonzero) digits is 3048192, while the sum is 54.

The spelling of 66121297038720 in words is "sixty-six trillion, one hundred twenty-one billion, two hundred ninety-seven million, thirty-eight thousand, seven hundred twenty".