18718720861 has 8 divisors (see below), whose sum is σ = 18887709240. Its totient is φ = 18549791232.

The previous prime is 18718720849. The next prime is 18718720871. The reversal of 18718720861 is 16802781781.

It can be written as a sum of positive squares in 4 ways, for example, as 271920100 + 18446800761 = 16490^2 + 135819^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 18718720861 - 2⁵ = 18718720829 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 (18718720841) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 856255 + ... + 877843.

It is an arithmetic number, because the mean of its divisors is an integer number (2360963655).

Almost surely, 2^18718720861 is an apocalyptic number.

It is an amenable number.

18718720861 is a deficient number, since it is larger than the sum of its proper divisors (168988379).

18718720861 is a wasteful number, since it uses less digits than its factorization.

18718720861 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 29375.

The product of its (nonzero) digits is 301056, while the sum is 49.

The spelling of 18718720861 in words is "eighteen billion, seven hundred eighteen million, seven hundred twenty thousand, eight hundred sixty-one".