1809985140 has 72 divisors (see below), whose sum is σ = 5501478528. Its totient is φ = 481679040.

The previous prime is 1809985109. The next prime is 1809985157. The reversal of 1809985140 is 415899081.

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

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 23 ways as a sum of consecutive naturals, for example, 80545 + ... + 100535.

It is an arithmetic number, because the mean of its divisors is an integer number (76409424).

Almost surely, 2^1809985140 is an apocalyptic number.

1809985140 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 1809985140, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2750739264).

1809985140 is an abundant number, since it is smaller than the sum of its proper divisors (3691493388).

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

1809985140 is a wasteful number, since it uses less digits than its factorization.

1809985140 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20509 (or 20504 counting only the distinct ones).

The product of its (nonzero) digits is 103680, while the sum is 45.

The square root of 1809985140 is about 42543.9201296731. The cubic root of 1809985140 is about 1218.6855726100.

The spelling of 1809985140 in words is "one billion, eight hundred nine million, nine hundred eighty-five thousand, one hundred forty".