861007721841 has 20 divisors (see below), whose sum is σ = 1286387720112. Its totient is φ = 573919908408.

The previous prime is 861007721839. The next prime is 861007721851. The reversal of 861007721841 is 148127700168.

861007721841 is a `hidden beast` number, since 8 + 610 + 0 + 7 + 7 + 21 + 8 + 4 + 1 = 666.

It is not a de Polignac number, because 861007721841 - 2¹ = 861007721839 is a prime.

It is not an unprimeable number, because it can be changed into a prime (861007721801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 19 ways as a sum of consecutive naturals, for example, 238071 + ... + 1333676.

Almost surely, 2^861007721841 is an apocalyptic number.

861007721841 is a gapful number since it is divisible by the number (81) formed by its first and last digit.

It is an amenable number.

861007721841 is a deficient number, since it is larger than the sum of its proper divisors (425379998271).

861007721841 is a wasteful number, since it uses less digits than its factorization.

861007721841 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1578522 (or 1578513 counting only the distinct ones).

The product of its (nonzero) digits is 150528, while the sum is 45.

The spelling of 861007721841 in words is "eight hundred sixty-one billion, seven million, seven hundred twenty-one thousand, eight hundred forty-one".