1861107509 has 6 divisors (see below), whose sum is σ = 1925523990. Its totient is φ = 1796707080.

The previous prime is 1861107481. The next prime is 1861107539. The reversal of 1861107509 is 9057011681.

It can be written as a sum of positive squares in only one way, i.e., 1604403025 + 256704484 = 40055^2 + 16022^2 .

It is not a de Polignac number, because 1861107509 - 2⁸ = 1861107253 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1861107539) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 228314 + ... + 236324.

It is an arithmetic number, because the mean of its divisors is an integer number (320920665).

Almost surely, 2^1861107509 is an apocalyptic number.

It is an amenable number.

1861107509 is a deficient number, since it is larger than the sum of its proper divisors (64416481).

1861107509 is an frugal number, since it uses more digits than its factorization.

1861107509 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16051 (or 8040 counting only the distinct ones).

The product of its (nonzero) digits is 15120, while the sum is 38.

The square root of 1861107509 is about 43140.5552699545. Note that the first 3 decimals coincide. The cubic root of 1861107509 is about 1230.0529884414.

The spelling of 1861107509 in words is "one billion, eight hundred sixty-one million, one hundred seven thousand, five hundred nine".