66461589829440 has 336 divisors, whose sum is σ = 246272097668688. Its totient is φ = 16353975140352.

The previous prime is 66461589829429. The next prime is 66461589829447. The reversal of 66461589829440 is 4492898516466.

66461589829440 is a `hidden beast` number, since 6 + 6 + 4 + 6 + 158 + 9 + 8 + 29 + 440 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 3665601259776 + 62795988569664 = 1914576^2 + 7924392^2 .

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66461589829447) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 105754222 + ... + 106380818.

It is an arithmetic number, because the mean of its divisors is an integer number (732952671633).

Almost surely, 2^{66461589829440} is an apocalyptic number.

66461589829440 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 66461589829440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (123136048834344).

66461589829440 is an abundant number, since it is smaller than the sum of its proper divisors (179810507839248).

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

66461589829440 is a wasteful number, since it uses less digits than its factorization.

66461589829440 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 629466 (or 629453 counting only the distinct ones).

The product of its (nonzero) digits is 716636160, while the sum is 72.

The spelling of 66461589829440 in words is "sixty-six trillion, four hundred sixty-one billion, five hundred eighty-nine million, eight hundred twenty-nine thousand, four hundred forty".