61809441242778 has 192 divisors, whose sum is σ = 146862666437760. Its totient is φ = 18718957522944.

The previous prime is 61809441242771. The next prime is 61809441242779. The reversal of 61809441242778 is 87724214490816.

61809441242778 is a `hidden beast` number, since 6 + 1 + 80 + 9 + 441 + 2 + 42 + 7 + 78 = 666.

It is not an unprimeable number, because it can be changed into a prime (61809441242771) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 454704150 + ... + 454840062.

It is an arithmetic number, because the mean of its divisors is an integer number (764909721030).

Almost surely, 2^{61809441242778} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 61809441242778, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (73431333218880).

61809441242778 is an abundant number, since it is smaller than the sum of its proper divisors (85053225194982).

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

61809441242778 is a wasteful number, since it uses less digits than its factorization.

61809441242778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136493 (or 136490 counting only the distinct ones).

The product of its (nonzero) digits is 43352064, while the sum is 63.

The spelling of 61809441242778 in words is "sixty-one trillion, eight hundred nine billion, four hundred forty-one million, two hundred forty-two thousand, seven hundred seventy-eight".