1861288655 has 4 divisors (see below), whose sum is σ = 2233546392. Its totient is φ = 1489030920.

The previous prime is 1861288633. The next prime is 1861288657. The reversal of 1861288655 is 5568821681.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5568821681 = 3461 ⋅1609021.

It is a de Polignac number, because none of the positive numbers 2^k-1861288655 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1861288657) by changing a digit.

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 3 ways as a sum of consecutive naturals, for example, 186128861 + ... + 186128870.

It is an arithmetic number, because the mean of its divisors is an integer number (558386598).

Almost surely, 2^1861288655 is an apocalyptic number.

1861288655 is a deficient number, since it is larger than the sum of its proper divisors (372257737).

1861288655 is an equidigital number, since it uses as much as digits as its factorization.

1861288655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 372257736.

The product of its digits is 921600, while the sum is 50.

The square root of 1861288655 is about 43142.6547050596. The cubic root of 1861288655 is about 1230.0928951366.

The spelling of 1861288655 in words is "one billion, eight hundred sixty-one million, two hundred eighty-eight thousand, six hundred fifty-five".