18689567221 has 4 divisors (see below), whose sum is σ = 20127226252. Its totient is φ = 17251908192.

The previous prime is 18689567203. The next prime is 18689567231. The reversal of 18689567221 is 12276598681.

It is a happy number.

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

It can be written as a sum of positive squares in 2 ways, for example, as 9661907025 + 9027660196 = 98295^2 + 95014^2 .

It is a cyclic number.

It is not a de Polignac number, because 18689567221 - 2⁷ = 18689567093 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 (18689567201) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 718829496 + ... + 718829521.

It is an arithmetic number, because the mean of its divisors is an integer number (5031806563).

Almost surely, 2^18689567221 is an apocalyptic number.

It is an amenable number.

18689567221 is a deficient number, since it is larger than the sum of its proper divisors (1437659031).

18689567221 is a wasteful number, since it uses less digits than its factorization.

18689567221 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1437659030.

The product of its digits is 2903040, while the sum is 55.

The spelling of 18689567221 in words is "eighteen billion, six hundred eighty-nine million, five hundred sixty-seven thousand, two hundred twenty-one".