1981860205 has 16 divisors (see below), whose sum is σ = 2672530560. Its totient is φ = 1399894848.

The previous prime is 1981860161. The next prime is 1981860229. The reversal of 1981860205 is 5020681891.

It is a cyclic number.

It is not a de Polignac number, because 1981860205 - 2¹³ = 1981852013 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 661335 + ... + 664324.

It is an arithmetic number, because the mean of its divisors is an integer number (167033160).

Almost surely, 2^1981860205 is an apocalyptic number.

It is an amenable number.

1981860205 is a deficient number, since it is larger than the sum of its proper divisors (690670355).

1981860205 is a wasteful number, since it uses less digits than its factorization.

1981860205 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1325700.

The product of its (nonzero) digits is 34560, while the sum is 40.

The square root of 1981860205 is about 44518.0885146701. The cubic root of 1981860205 is about 1256.1003571497.

The spelling of 1981860205 in words is "one billion, nine hundred eighty-one million, eight hundred sixty thousand, two hundred five".