1981666350 has 192 divisors, whose sum is σ = 5679844800. Its totient is φ = 507617280.

The previous prime is 1981666327. The next prime is 1981666363. The reversal of 1981666350 is 536661891.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 1981666296 and 1981666305.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 4844946 + ... + 4845354.

It is an arithmetic number, because the mean of its divisors is an integer number (29582525).

Almost surely, 2^1981666350 is an apocalyptic number.

1981666350 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 1981666350, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2839922400).

1981666350 is an abundant number, since it is smaller than the sum of its proper divisors (3698178450).

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

1981666350 is a wasteful number, since it uses less digits than its factorization.

1981666350 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 564 (or 553 counting only the distinct ones).

The product of its (nonzero) digits is 233280, while the sum is 45.

The square root of 1981666350 is about 44515.9112003787. The cubic root of 1981666350 is about 1256.0594008007.

The spelling of 1981666350 in words is "one billion, nine hundred eighty-one million, six hundred sixty-six thousand, three hundred fifty".