1661560691056 has 160 divisors (see below), whose sum is σ = 3735635904000. Its totient is φ = 701267632128.

The previous prime is 1661560690987. The next prime is 1661560691057. The reversal of 1661560691056 is 6501960651661.

It is a junction number, because it is equal to n+sod(n) for n = 1661560690994 and 1661560691012.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1661560691057) 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 31 ways as a sum of consecutive naturals, for example, 1938810180 + ... + 1938811036.

It is an arithmetic number, because the mean of its divisors is an integer number (23347724400).

Almost surely, 2^{1661560691056} is an apocalyptic number.

1661560691056 is a gapful number since it is divisible by the number (16) 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 1661560691056, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1867817952000).

1661560691056 is an abundant number, since it is smaller than the sum of its proper divisors (2074075212944).

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

1661560691056 is a wasteful number, since it uses less digits than its factorization.

1661560691056 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1791 (or 1785 counting only the distinct ones).

The product of its (nonzero) digits is 1749600, while the sum is 52.

The spelling of 1661560691056 in words is "one trillion, six hundred sixty-one billion, five hundred sixty million, six hundred ninety-one thousand, fifty-six".