861381787 has 4 divisors (see below), whose sum is σ = 984436336. Its totient is φ = 738327240.

The previous prime is 861381757. The next prime is 861381791. The reversal of 861381787 is 787183168.

It is a semiprime because it is the product of two primes.

It is not a de Polignac number, because 861381787 - 2⁷ = 861381659 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 861381787.

It is not an unprimeable number, because it can be changed into a prime (861381707) 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, 61527264 + ... + 61527277.

It is an arithmetic number, because the mean of its divisors is an integer number (246109084).

Almost surely, 2^861381787 is an apocalyptic number.

861381787 is a deficient number, since it is larger than the sum of its proper divisors (123054549).

861381787 is a wasteful number, since it uses less digits than its factorization.

861381787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 123054548.

The product of its digits is 451584, while the sum is 49.

The square root of 861381787 is about 29349.3064142920. The cubic root of 861381787 is about 951.4775850379.

The spelling of 861381787 in words is "eight hundred sixty-one million, three hundred eighty-one thousand, seven hundred eighty-seven".