18866841721 has 16 divisors (see below), whose sum is σ = 24021446400. Its totient is φ = 14412863808.

The previous prime is 18866841709. The next prime is 18866841733. The reversal of 18866841721 is 12714866881.

It is an interprime number because it is at equal distance from previous prime (18866841709) and next prime (18866841733).

It is not a de Polignac number, because 18866841721 - 2⁷ = 18866841593 is a prime.

It is not an unprimeable number, because it can be changed into a prime (18866841221) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3571981 + ... + 3577258.

It is an arithmetic number, because the mean of its divisors is an integer number (1501340400).

Almost surely, 2^18866841721 is an apocalyptic number.

It is an amenable number.

18866841721 is a deficient number, since it is larger than the sum of its proper divisors (5154604679).

18866841721 is a wasteful number, since it uses less digits than its factorization.

18866841721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7149288.

The product of its digits is 1032192, while the sum is 52.

The spelling of 18866841721 in words is "eighteen billion, eight hundred sixty-six million, eight hundred forty-one thousand, seven hundred twenty-one".