61665398782416 has 1800 divisors, whose sum is σ = 224087579476992. Its totient is φ = 16327248537600.

The previous prime is 61665398782399. The next prime is 61665398782417. The reversal of 61665398782416 is 61428789356616.

61665398782416 is a `hidden beast` number, since 6 + 1 + 6 + 6 + 53 + 9 + 87 + 82 + 416 = 666.

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 (61665398782417) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 359 ways as a sum of consecutive naturals, for example, 38613273330 + ... + 38613274926.

Almost surely, 2^{61665398782416} is an apocalyptic number.

61665398782416 is a gapful number since it is divisible by the number (66) 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 61665398782416, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (112043789738496).

61665398782416 is an abundant number, since it is smaller than the sum of its proper divisors (162422180694576).

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

61665398782416 is a wasteful number, since it uses less digits than its factorization.

61665398782416 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1743 (or 1704 counting only the distinct ones).

The product of its digits is 627056640, while the sum is 72.

The spelling of 61665398782416 in words is "sixty-one trillion, six hundred sixty-five billion, three hundred ninety-eight million, seven hundred eighty-two thousand, four hundred sixteen".