1661617420980 has 144 divisors (see below), whose sum is σ = 5154206668800. Its totient is φ = 399644340480.

The previous prime is 1661617420973. The next prime is 1661617421017. The reversal of 1661617420980 is 890247161661.

It is a Smith number, since the sum of its digits (51) coincides with the sum of the digits of its prime factors.

It is a congruent number.

It is an unprimeable number.

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 47 ways as a sum of consecutive naturals, for example, 20946 + ... + 1823094.

Almost surely, 2^{1661617420980} is an apocalyptic number.

1661617420980 is a gapful number since it is divisible by the number (10) 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 1661617420980, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2577103334400).

1661617420980 is an abundant number, since it is smaller than the sum of its proper divisors (3492589247820).

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

1661617420980 is a wasteful number, since it uses less digits than its factorization.

1661617420980 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1802310 (or 1802297 counting only the distinct ones).

The product of its (nonzero) digits is 870912, while the sum is 51.

The spelling of 1661617420980 in words is "one trillion, six hundred sixty-one billion, six hundred seventeen million, four hundred twenty thousand, nine hundred eighty".